material laid between a subfloor and a finish floor of linoleum, asphalt tile, etc
Word origin
[1945–50; underlay + -ment]This word is first recorded in the period 1945–50. Other words that entered Englishat around the same time include: RNA, ergative, on-line, regression analysis, synchronized swimming-ment is a suffix of nouns, often concrete, denoting an action or resulting state (abridgment; refreshment), a product (fragment), or means (ornament)