abbreviation , exclamation
■ abbreviation
millimetre(s) :
rainfall 6mm
a 35mm camera
■ exclamation
(also mmm ) the way of writing the sound /m/ that people make to show that they are listening to sb or that they agree, they are thinking, they like sth, they are not sure, etc. :
Mm, I know what you mean.
Mm, what lovely cake!
Mmm, I'm not so sure that's a good idea.