Yes, mils is a Scrabble word!

Noun

1. A Cypriot monetary unit equal to one thousandth of a pound

2. A Swedish unit of length equivalent to 10 km

3. A unit of length equal to one thousandth of an inch; used to specify thickness (e.g., of sheets or wire)

4. A metric unit of volume equal to one thousandth of a liter

5. An angular unit used in artillery; equal to 1/6400 of a complete revolution