|Mil is also a term for one [tenth] of a [cent] (or one [thousandth] of a dollar) in U.S. [currency]. Often seen on [ballot|ballots], where a certain [referendum] might ask for a couple of mils per [dollar] of [taxes] for some worthy [cause]. Webster says that this is spelled [mill], but common usage seems to be divided evenly between the two spellings.
Mil can also mean :
[One million dollars] ([colloquial])
.mil is also one of the [top level domain]s for internet names : see [RFC 1956 (Registration in the MIL Domain)].
[Thousand] in the context of "particles found at a [density] of 37.5 per mil".
A [monetary unit] formerly used in [Cyprus] equal to 1/1000 pound. (Currently Cyprus uses [Cyprus Pounds] or [CYP])
A unit of angular measurement equal to 1/6400 of [360 degrees] and used especially in artillery (that's 9/160 degrees or 0.05625 [degree|degrees] or 3 [minute|minutes] and 22.5 [second|seconds])
As [ModernAngel] said,
1/1000th of 1 [inch]. [Human] [hair] is about  mils thick. Industrial laminates (such as [laminate]d [cable shield]) may be composed of [foil] and [plastic] only tenths of a mil in thickness.
Short for [Mother-In-Law], according to [dem bones].