mM

The word “mM” means abbreviation for millimetre, a unit of length equal to one-thousandth of a metre. In plain terms, the short written form of "millimetre(s).".

Here is “mM” used in a sentence: “The screw was only 3 mm in diameter.”

“MM” is a noun.

“MM” is a fairly common word in modern English.

There are ten millimetres in one centimetre. The millimetre is the smaller unit, so to convert centimetres to millimetres you multiply by ten, and to go the other way you divide by ten. For example, 5 cm equals 50 mm, and 30 mm equals 3 cm.

One metre contains 1,000 millimetres, since a millimetre is defined as one-thousandth of a metre. To convert metres to millimetres you multiply by a thousand, so 2 metres is 2,000 mm. This makes the millimetre a convenient unit for measuring small objects and fine details accurately.

Millimetres suit small lengths where precision matters. Rainfall totals, the thickness of a phone, screw and drill sizes, paper dimensions, and gaps in engineering parts are all commonly given in millimetres. It is a standard unit in construction, manufacturing, science, and design wherever accuracy to a fraction of a centimetre is needed.