originally. Leaven or yeast. Hence gen. an agent which causes fermentation (see fermentation, n. 1).

One who, or that which, excites; †an instigator.

figurative. A thing that inflames or excites passion, strife, etc.; an incentive to evil. Obsolete.

A person who or thing which electrifies something (literal and figurative).

= exciter, n.

The action of filling with liveliness, enlivenment; the result of this; enlivening operation or influence. Now rare.

Something which shocks or excites; esp. a work of fiction of a sensational character. Also, something or someone shockingly bad. Also attributive.

A person or thing liable to arouse intense emotions; someone or something inspiring excitement, suspense, or passion. Cf. heart-stopper, n.

A situation, incident, etc., that is full of suspense or exciting.

A lively, exciting time or event, esp. in Sport. Originally and chiefly U.S.

The action or an instance of turning somebody on; a drug-taker's ‘trip’; something which or someone who arouses interest, enthusiasm, or sexual…

figurative. Something likened to the G-spot (sense 1) in being a source of great pleasure, excitement, or satisfaction.