sub.

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.

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.

To subtitle (usually a film or television program).

To lend (a person) money.

To subscribe.

To take a submissive role.

Under.

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.

Abbreviation of submarine.

Clipping of submarine sandwich: a sandwich made on a long bun.

We can get subs at that deli.

Clipping of submersible.

Clipping of substitute, often in sports or teaching.

With the score 4 to 1, they brought in subs.

She worked as a sub until she got her teaching certificate.

Clipping of subscription (“a payment made for membership of a club, etc.”).

Clipping of subtitle

I've just noticed a mistake in the subs for this film.

Clipping of subroutine (sometimes one that does not return a value, as distinguished from a function, which does)

Clipping of subeditor

Clipping of subcontractor

Clipping of subwoofer

Clipping of submission (of a work for publication).

Clipping of submissive

Clipping of subordinate

Clipping of subaltern

Clipping of subscription (or (by extension) a subscriber) to an online channel or feed.

I'm totally stoked; just got 10 new subs after my last video.

Clipping of subsistence money, part of a worker's wages paid before the work is finished.

Clipping of subreddit.

That sub had so much politics to the point that I unfollowed it entirely.

Clipping of subject (“particular area of study”)

Clipping of subliminal (“an audio or video recording intended to produce physical or psychological changes in the listener”)