1 quick, ready, immediate, instantaneous, unhesitating, rapid, fast, swift, speedy, punctual, timely, on time, instant, summary, brisk, alacritous:
No matter what the question, Gemma gave a prompt response.
2 alert, eager, ready, quick, expeditious, ready and willing, disposed, predisposed, unhesitating, keen, avid:
Slow to praise, Alan was always prompt to criticize.
3 urge, egg (on), prod, nudge, spur, exhort, incite, induce, impel, provoke, rouse, arouse, encourage, work or stir or fire up, move, motivate, cause, influence, put (someone) up to (something), coax, persuade, cajole, prevail upon or on, talk (someone) into (something):
If he hadn't prompted her, she never would have apologized.
4 cue, remind, feed lines (to), help:
She never could remember her lines and needed to be prompted.
5 bring about, inspire, occasion, give rise to, elicit, evoke, provoke, call forth, stimulate, awaken:
The mention of hostages prompted a question about what was being done to gain their release.
6 reminder, cue, hint, stimulus:
He always needs a prompt to remind him to send his mother flowers on her birthday.