A ThermoWorks Glossary

absolute zero The coldest possible temperature, zero on the Kelvin scale, or approximately −273.15 °C, −459.67 °F
accuracy The closeness of the agreement between the result of a measurement and the value of the quantity being measured and or "true value." Usually expressed as ± a certain number of degrees or ± a certain percentage of the full reading.
adjustable emissivity A setting on many infrared thermometers allowing you to help the thermometer calculate a more accurate temperature reading for a given material based on an estimate of its ability to emit infrared energy. See emissivity.
ANSI An acronym for American National Standards Institute. A private non-profit organization that oversees the development of voluntary standards for products and services and coordinates those standards with international standards so that American products can be used worldwide.
auto-off The ability of a device to turn itself off to conserve power after a specified period of time without any user inputs. In many cases, this function can itself be disabled so the device can be used for extended periods without interruption.
auto-range A feature on some thermometers that automatically changes the resolution of the display over a specified range.
background noise The total noise floor from all sources of interference in a measurement system, independent of the presence of a data signal.
blackbody A theoretical material that absorbs all incident electromagnetic radiation and reflects none. Also used to describe devices that approximate the theoretical standard for the calibration of infrared thermometers.
boiling point The temperature at which a substance in the liquid phase transforms to the gaseous phase. Typically refers to the boiling point of water which is 212°F (100°C) at sea level but which varies with changes in elevation and barometric pressure. See our Boiling Point Calculator. 
calibration The process of adjusting an instrument to be more accurate by comparing it to a reliable standard. Often includes the compilation of a deviation chart showing actual test results and/or a certificate. See NIST-Traceable.
calibration bath A uniform temperature enclosure using carefully stirred fluid to provide excellent thermal contact and uniformity for temperature calibration.
cavitation The boiling of a liquid caused by a decrease in pressure rather than an increase in temperature.
Celsius A metric scale of temperature, originally defined as having the freezing point of water as 0° and its boiling point as 100°, at standard atmospheric pressure. The standardized definition has 0.01° C as the triple point of water, and a difference in temperature of 1° C corresponds to 1/273.16 of the difference in temperature between the triple point and absolute zero. Used throughout the world but not commonly used in the United States except in laboratories and scientific applications.
centigrade A temperature scale based on 100 degrees of difference between the freezing and boiling points of water. Commonly used to refer to Celsius.
clear To restore a device to a its initial state, usually the zero state.
compensation An addition of specific materials or devices to counteract a known error.
conduction The transfer of electrical energy or heat through or by means of a conductor.
constantan A copper-nickel alloy used as the negative lead in Type E, Type J, and Type T thermocouples.
control point The temperature at which a system is to be maintained.
controller A device that regulates the power supply to a heater or bath to bring it up to a specified temperature.
convection The transfer of heat by the circulation of fluid or gas.
data logger An electronic device that records temperature data at a specific location at regular intervals over time with either a built-in sensor or through external sensors or probes. Data can typically be downloaded into a spreadsheet or database file. Particularly useful for showing that stored items stayed within a certain temperature range over time.
degree A unit of measurement of temperature on any of several scales, such as Celsius or Fahrenheit.
dew point The air temperature at which, under current barometric pressure, the water vapor currently in the air would condense into water or dew (or reach 100% humidity)
dia. Diameter. Typically in reference to the physical dimensions of a probe or instrument.
DIN An acronym for Deutsche Industrial Norm. A set of German standards recognized throughout the world. For example, DIN 43760 is the standard defining the characteristics of a 100 ohm PRT having a resistance vs. temperature curve specified by a = 0.00385 ohms per degree.
Distance to Target Ratio "Indicates the diameter of the surface area an infrared thermometer will measure at a given distance. An IR thermometer with a 50:1 ratio will average the temperature of a one-inch diameter circle (spot size) of surface area from 50 inches away and a 2-inch diameter circle from 100 inches away and so on. Also called ""spot ratio.""
drift The change in the readings or measurement values of an instrument at a set point over time. See calibration.
dry well A portable calibration furnace that uses narrow metal enclosures rather than liquid to generate uniformity at thermal contact for pre-set temperatures.
E. coli A group of bacteria, Escherichia, that reside in the intestinal tracts of humans and many animals and can cause food poisoning, urinary infections and enteritis.
emissivity A measure of the energy-emitting propensity of a surface, usually measured at a specific wavelength. Used by infrared thermometers to calculate temperatures based on infrared emissions. Most organic materials have an emissivity of 0.95. \
Fahrenheit A scale of temperature originally defined by having 0° as the lowest obtainable temperature with a mixture of water, ice and salt and 96° as the temperature of the human body. The standardized definition has 32° as the ice point of water and 212° as the boiling point of water at standard atmospheric pressure. Used primarily in the United States. 
HACCP An acronym for Hazard Analysis Critical Control Point. A systematic approach to food safety that identifies critical physical, chemical and biological hazards in the , so that actions can be taken to reduce or eliminate the risk. Mandated by the USDA and FDA for certain foods and processes.
hi/low alarm A feature common to thermometers that will alert you via visual and/or audible cues (or, in some cases, email or texts) when a measurement is outside user-specified limits for safety or desirability. Common to data loggers as well.
hold A feature common to thermometers allowing you to freeze the display at a given measurement without additional inputs for easier reading. Sometimes called "lock."
hygrometer An instrument that measures the humidity of the air or other gases, especially the relative humidity.
hysteresis A quality of a system such that the output is not only determined by the input but also by the internal state of the system, particularly as it is affected by previous measurements. Thermometers exhibiting hysteresis will give different readings at the same temperature when measurements are taken consecutively. Sometimes letting an instrument rest for an extended period between measurements will minimize the impact of hysteresis. See repeatability.
infrared A type of thermometry that measures the amount of infrared energy being emitted by a substance and compares that value to a predictable curve to calculate temperature.
IP rating A measure of an instrument's protection against the ingress of dust, water and other substances into the equipment. See the product specification table for the actual test rating. See also our IP Table.
Kelvin An absolute, thermodynamic temperature scale using as its null point absolute zero and the triple point of water at 273.16 K (0.01 °C; 32.02 °F). The kelvin is defined as 1/273.16 of the difference between these two reference points. Used in scientific research.
Listeria A rod-shaped bacteria common to food.
lock See hold.
max/min A common thermometer feature allowing you to quickly display the maximum and/or minimum values measured during a specified period of time.
NIST-Traceable Indicates that a given instrument has been calibrated using standards that have an accuracy certified by the National Institute of Standards and Technology (NIST). 
NSF Certified This icon indicates that the design, materials, production process and quality controls used in the production of a product have been verified and certified for food safety by a highly respected third party non-profit organization, the National Sanitation Foundation (NSF).
pH A measure of the acidity or alkalinity of a substance, using numerical values from 0 (maximum acidity) through 7 (neutral) to 14 (maximum alkalinity).
precision See resolution.
PRT An acronym for Platinum Resistance Thermometer. The most common type of RTD that uses changes in electrical resistance on a platinum circuit board to calculate temperature. Known for its precision, stability and accuracy over a wide range, the PRT is actually a probe commonly used in calibration laboratories.
range The values that a particular instrument is intended to measure, usually noted in a specification table by upper and lower limits.
relative humidity The ratio of the actual amount of water vapor (absolute humidity) present in the air to the saturation point at the same temperature, usually expressed as a percentage.
repeatability The ability of an instrument to reproduce the same output reading when the same input value is applied to it consecutively (measuring the same temperature). Repeatability is sometimes expressed in a specification table as the maximum difference between consecutive output readings.
reproducibility See repeatability.
resistance The resistance to the flow of electric current measured in ohms. Used by thermistors and RTDs to calculate temperature.
resolution The smallest detectable increment of measurement on an instrument. A thermometer that displays temperature readings to the hundredth of a degree (e.g. 100.26°) has a greater resolution than one that only shows the tenths of a degree (e.g. 100.3°) or whole degrees (100°). Also called "precision."
response time The length of time a given instrument requires to reach a specified percentage of its final reading value. Often expressed in a specification table in "time constants."
RTD Resistance Thermometer Detection probes use variance in resistance (typically in platinum) to calculate temperatures—known for high accuracy over a wide range of temperatures and low drift—typical in high-precision applications like calibration.
Salmonella A rod-shaped bacteria common to food, particularly chicken and chicken products like eggs. Known for causing food poisoning. 
speed See response time.
splash-proof A non-technical term used to describe instruments that are protected from ingress caused by the splashing of liquids but not necessarily protected against immersion. See IP rating.
spot ratio See Distance to Target Ratio.
spot size The diameter of the circle formed by the intersection of the field of view of an infrared thermometer with the surface being measured. See Distance to Target Ratio. 
stability The ability of an instrument or sensor to maintain a consistent output when a constant input is applied over time. A calibration bath, for example, is considered to have high stability if the actual value of the temperature in the bath only varies by hundredths of a degree over an hour.
Staphylococcus A microscopic bacteria common to skin and mucous membranes. Shaped like grape clusters. Most are harmless but some can cause illness. 
Teflon A registered trademark. Materials made with polytetrafluoroethylene (PTFE) known for its resistance to high temperature and chemical corrosion.
thermistor A common thermal sensor that uses the predictable variance in the resistance to an electrical current with changes in temperature to calculate temperatures
thermocouple The sensor of a thermoelectric thermometer, consisting of electrically conducting circuit elements of two different thermoelectric characteristics joined at a junction.
thermometer An instrument used to measure temperature.
time constant As defined by engineering sciences, a time constant is the actual time that a physical system requires to reach 62.3% of its total value. After 5 time constants, the system is considered to be at 100% value.
Type J A specialized thermocouple sensor pairing two wires made mostly of iron and constantan and using variance in voltage to calculate temperatures—more limited in its range to higher temperatures but known for its sensitivity. 
Type K A common thermocouple sensor pairing two wires made mostly of nickel and chromium and using variance in voltage to calculate temperatures—known for its wide temperature range and affordability—typical in industrial applications.
Type T A more specialized thermocouple sensor pairing two wires made mostly of copper and constantan and using variance in voltage to calculate temperatures—known for greater accuracy and durability—typical in medical or pharmaceutical applications.
UKAS An acronym for United Kingdom Accreditation Service, the organization tasked by the British government with the maintenance and administration of national standards. Fully consistent with American NIST standards through the ISO/IEC 17025 international standard. 
uncertainty An expression of the possible measurement error for a given instrument over a specified range. Usually expressed as ± a certain number of degrees or ± a certain percentage of the full reading. See accuracy.
water-resistant A non-technical term used to describe instruments that are protected from the ingress of water. See IP rating
waterproof A non-technical term used to describe instruments that are protected from the ingress of water. See IP rating