steam

Concise Oxford English Dictionary © 2008 Oxford University Press:
steam/stiːm/

▶noun

• 1 the hot vapour into which water is converted when heated, which condenses in the air into a mist of minute water droplets.

• 2 the expansive force of this vapour used as a source of power for machines.

• 3 momentum; impetus: the dispute gathered steam.

▶verb

• 1 give off or produce steam.

  ■ (steam up or steam something up) become or cause something to become misted over with steam.

• 2 cook (food) by heating it in steam from boiling water.

  ■ clean or otherwise treat with steam.

  ■ apply steam to (something fixed with adhesive) so as to open or loosen it.

• 3 (of a ship or train) travel somewhere under steam power.

  ■ informal come, go, or move somewhere rapidly or in a forceful way.

  ■ generate steam in and operate (a steam locomotive).

• 4 (be/get steamed up) informal be or become extremely agitated or angry.

– phrases
get up (or pick up) steam

• 1 generate enough pressure to drive a steam engine.

• 2 (of an activity, project, etc.) gradually gain impetus.

have steam coming out of one's ears informal be extremely angry.
let (or blow) off steam informal get rid of pent-up energy or strong emotion.
run out of (or lose) steam informal lose impetus or enthusiasm.
under one's own steam without assistance from others.

– origin OE stēam ‘vapour’, stēman ‘emit a scent, be exhaled’, of Gmc origin.