Science often borrows words from general use and gives them a specific meaning. For example the word 'weight' when used by a normal person means the same as 'mass' when used by a scientist. And when a scientist uses the word 'weight' they mean something else entirely...

The same goes for the word 'colour'. Most people think of colour in terms of a rainbow, but some types of subatomic particles (like quarks) have a property called 'colour'. They can be red, green or blue and, slightly disturbingly, they can also be anti-red, anti-green or anti-blue. They are much smaller than the wavelength of visible light, so they cannot be seen.

Other Examples

Here are some other examples of specialised words.

Alcohol: In layman's speech this is the thing in beer/wine/whisky/whatever that makes you dizzy. In the scientific sense alcohol is a group of organic compounds characterised by the -OH or hydroxyl-group. The layman's alcohol, in the correct nomenclature, is known as ethanol.

Mood: When this word is used by the general population, they're referring to whether you are happy or sad or somewhere in-between. However, linguists use it as a grammatical category, hence the subjunctive, imperative and indicative moods.

Blues: A style of music rather than the primary colour which isn't red or yellow.

Colour Temperature: In colour photography, you use the term colour temperature to refer to the quality of the light source as it affects film's ability to register colour properly.

For instance, indoor lighting has a lower colour temperature than sunlight, so if you use regular (daylight) film inside without a flash, the colour will be too brown. The flash of the camera is balanced to have a similar colour temperature to daylight (before they could accomplish this they used blue flashbulbs to compensate). Tungsten film is balanced for indoor lighting. Colour temperature is expressed in degrees Kelvin.

The term originates from thermodynamics. A certain colour temperature is a parameter of the Planck function of a blackbody at a certain wavelength. That is, if you have a blackbody that has a Planck function with a maximum at, say 450nm, then the associated colour temperature would be 5000 K.

Dynamics: In physics, dynamics relates to a physical force or energy. In music, the term is used to describe the volume of the sound being created: as in how loud or soft it is.

Ego: In psychology, ego is a term first used by Freud to describe three basic components of human personality: id, or the basic drives, that component that lacks moral judgement and is unconscious; ego, the component that develops to act as a mediator between the id and reality, operating according to the reality principle and allowing the delay of impulses until the situation is appropriate; and the superego, which includes the conscience, ideals and values acquired from society. The superego (according to Freud) also acts to suppress sexual impulses. The ego acts as a supervisor, negotiating a compromise between the libidinous id and the rule-driven, moralistic superego. For more information on the subject, see Psychodynamic Theory.

Generally: When a mathematician uses the word generally, s/he means without exception. However, the layman uses the same term to mean admitting exceptions!

Hacker: The generally held meaning of the word hacker (as in some kind of nerdy misanthrope who evilly ruins other peoples' computer systems) is not what real geeks (who know about these things) mean when they call somebody a hacker. A hacker means someone good at programming. Hackers call what the general public call hackers, 'crackers' or sometimes script kiddies: a derogatory term. Crackers tend to call themselves things along the lines of K3wl Do0dZ. Also, within the golfing lexicon, a hacker is someone who is really bad at the game.

Implies: Ordinarily, if you say something implies something else you mean that the second even is a likely or even very likely consequence of the first. However in maths and formal logic, A implies B means that if A is true, B is certain to be true (although the reverse of this, B being true meaning A is true, is not always the case).

IPA: This can either refer to India Pale Ale and also Iso Propyl Alcohol. India Pale Ale was brewed in the UK with an extra high alcohol content so that it could be shipped safely to parts of the British Empire, notably to India: hence its name. There are still some breweries both in the UK and India which make it. Iso Propyl Alcohol, also known as Isopropanol or Propanol, is used in labs for cleaning things, like silicon wafers.

Jamming: Among microwave technicians, jamming is artificially-induced, high power signal noise, intended to mask the true return signal. To others it means an informal musical improvisation session, an event which inspired the likes of Bob Marley's eponymous song, Jamming.

Moment: In physics and engineering, a moment is the turning effect of a force. The moment of a force about an axis is the product of the force and the distance from where the force is applied to the axis. Otherwise, if you're a 'having a moment' you might be Californian, you'll probably be slightly spiritual in outlook and, as the result of some heavy duty meditation, you're experiencing a flash of clarity. Lucky you.

Noise: Among microwave technicians, noise refers to signal 'spikes' or aberrations that are not a part of the intended signal. When viewed on an oscilloscope, also (colloquially) called 'grass'.

Specific: In physics, this often means rate per unit. For example Specific Heat Capacity is the heat capacity per kilogram of a substance.

Strain: In physics and engineering, strain refers to displacements.

Strangeness: In sub-atomic physics, a particle can be assigned a quantity known as strangeness. This may be because while observing the time various particles took to decay, one took longer than usual. Someone noted that that was a strange particle, and the name stuck. Strangeness is in itself strange because any 'non-anti' particle with some strangeness has negative strangeness, whereas anti-particles have positive strangeness. This is caused by the 'lets have a guess and call this one positive - oops it's wrong' syndrome, as seen with the problems between conventional current and electron flow.

Stress: In physics and engineering, stress refers to internal forces inside an object.

Subliminal: Subliminal has come to mean unconscious processing of a stimulus (for example, in subliminal advertising). In fact, subliminal refers to below threshold stimulation in neuroscientific terms - prior to conscious or unconscious processing - and therefore subliminal advertising is supraliminal, but unattended...

Work: In physics and engineering, work is what a force does when it causes a displacement. Work is the product of the force and the displacement.