I. mm¹
the written abbreviation of millimetre or millimetres

[TahlilGaran] Dictionary of Contemporary English ▲

II. mm² /m/
used when someone else is speaking and you want to show that you are listening, that you agree with them, or that you are thinking about what they have said:
‘That’s okay, isn’t it?’ ‘Mm yeah.’
Mm, I see what you mean.

[TahlilGaran] Dictionary of Contemporary English ▲

MM
Mensa Member 
Mike Mike (military slang for millimeter) 
Million (oil industry) 
Multi-Media

[TahlilGaran] Acronyms and Abbreviations Dictionary ▲

M.M.
Mercantile Marine

[TahlilGaran] Acronyms and Abbreviations Dictionary ▲

m.m.
Made merchantable

[TahlilGaran] Acronyms and Abbreviations Dictionary ▲