Entries - M

mass

The quantity of matter which a body contains, as measured by its acceleration under a given force or by the force exerted on it by a gravitational field. Do not confuse with weight.

physics

massive

"Has mass" – the opposite of "massless". Does not mean "is large".

Though the up quark is a massive particle, it is not very big.

physics

maths

Not "math", as the shortened form of "mathematics".

style

may or might?

The subtle distinctions between these (and between other so-called modal verbs) are gradually disappearing, but they still matter to many readers and can be useful.

grammar

meet, met

Do not add the word "with" after meet or met. Write:

I met John the other day and tomorrow I will meet his wife. 

Not:

I met with John the other day and tomorrow I will meet with his wife. 

grammar

member state

Lower case

style

meson

A subatomic particle made of a quark and an antiquark.

physics

mid-

mid-50s

mid-90s

mid-week

mid-season

But midday

style

might or may?

See may or might?

grammar

millisieverts

Measure of radiation dose; symbol mSv

See sievert.

physics

moon

Always lower case.

multidisciplinary

No hyphen.

style

multipurpose

One word, no hyphen.

spelling, style

muon

An unstable subatomic particle of the same class as an electron (a lepton), but with a mass around 200 times greater. Muons make up much of the cosmic radiation reaching the Earth’s surface.

physics

MW

megawatts

mW

milliwatts

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