Definition

noun

A submarine.
A submarine sandwich: a sandwich made on a long bun.
“We can get subs at that deli.”
A substitute, often in sports.
“She worked as a sub until she got her teaching certificate.”
(often in plural) A subscription: a payment made for membership of a club, etc.
A subtitle.
“I've just noticed a mistake in the subs for this film.”

verb

To substitute for.
To work as a substitute teacher, especially in primary and secondary education.
To replace (a player) with a substitute.
“He never really made a contribution to the match, so it was no surprise when he was subbed at half time.”
Less commonly, and often as sub on, to bring on (a player) as a substitute.
“He was subbed on half way through the second half, and scored within minutes.”
To perform the work of a subeditor or copy editor; to subedit.

verb

To coat with a layer of adhering material; to planarize by means of such a coating.
To prepare (a slide) with a layer of transparent substance to support and/or fix the sample.