torr
Low. Highly specialized term used primarily in scientific and technical contexts.Formal, technical, scientific.
Definition
Meaning
A unit of pressure equal to 1/760 of a standard atmosphere (approximately equal to the pressure exerted by a one-millimetre column of mercury).
Primarily used in vacuum science and meteorology to measure low pressures. Named after Evangelista Torricelli, the inventor of the barometer.
Linguistics
Semantic Notes
The torr is effectively equivalent to one millimetre of mercury (mmHg), though the two units have a slight technical difference in definition (torr is defined by 1/760 atm, mmHg by the density of mercury). In practice, they are used interchangeably for most applications.
Dialectal Variation
British vs American Usage
Differences
No significant regional difference in meaning or usage, as it is a standard scientific unit.
Connotations
Technical precision; associated with physics, engineering, and laboratory work.
Frequency
Equally low frequency in both dialects, confined to specific fields.
Vocabulary
Collocations
Grammar
Valency Patterns
[Number] torra pressure of [Number] torrevacuate to [Number] torrVocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Usage
Context Usage
Business
Rare. Might appear in technical specifications for industrial vacuum equipment.
Academic
Common in physics, chemistry, and engineering papers dealing with pressure, vacuum technology, or gas laws.
Everyday
Virtually never used.
Technical
The primary context. Used in laboratory reports, equipment manuals, and engineering discussions about vacuum systems.
Examples
By Part of Speech
noun
British English
- The chamber was evacuated to a base pressure of 10^-3 torr.
- Older barometers in the UK often used scales marked in torr.
- The difference is negligible, only a few millitorr.
American English
- The vacuum pump can achieve a pressure of 5 x 10^-6 torr.
- The specification calls for a vacuum of less than 500 mtorr.
- They calibrated the sensor against a known torr standard.
Examples
By CEFR Level
- In our physics lab, we measured pressure in torr.
- A standard atmosphere is defined as 760 torr.
- The reaction proceeds efficiently at a reduced pressure of 0.5 torr.
- Modern gauges often display pressure in torr, pascal, and millibar simultaneously.
- The discrepancy between the calculated and observed vapour pressure was within 0.1 torr.
Learning
Memory Aids
Mnemonic
Think of TORR-icelli, who invented the barometer. A TORR is the pressure his instrument would show for a 1mm rise of mercury.
Conceptual Metaphor
PRESSURE IS A HEIGHT (of a liquid column).
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Avoid translating directly as "тор" (which is a bull in a bullfight). The correct equivalent is "торр" or the descriptive "миллиметр ртутного столба" (mmHg).
Common Mistakes
- Pronouncing it like 'tore' with a clear /r/ in non-rhotic (British) accents—it should be a long vowel /tɔː/.
- Using it for high-pressure contexts (it's for low/medium vacuum pressures).
- Confusing 'torr' with 'tor' (a rocky peak).
Practice
Quiz
Which of the following is the closest equivalent to one torr?
FAQ
Frequently Asked Questions
For almost all practical purposes, yes. 1 torr is defined as 1/760 of a standard atmosphere, while 1 mmHg is defined as the pressure exerted by a 1mm column of mercury at 0°C under standard gravity. The numerical difference is less than 0.000015%, so they are used interchangeably.
Primarily in vacuum science and technology, semiconductor manufacturing, physics and chemistry experiments involving low pressures, and sometimes in meteorology and barometry.
A millitorr (mTorr) is one-thousandth of a torr. It is a common subunit for expressing very low vacuum pressures.
No, the torr is not part of the International System of Units (SI). The SI unit for pressure is the pascal (Pa). 1 torr is approximately equal to 133.322 Pa.