— Suddenly she felt a sharp pain in her side.
Quickly and without warning:
— He stopped suddenly.
Roget 508: abruptly, unexpectedly, surprisingly; plump, pop, a l'improviste [Fr.], unawares; without notice, without warning, without a 'by your leave';" like a thief in the night, like a thunderbolt; in an unguarded moment; ... show more
On impulse; without premeditation:
— He made up his mind suddenly.
synonym: on the spur of the moment.
Moby thesaurus: a corps perdu, aback, abruptly, all at once, bang, by surprise, dash, feverishly, fleetingly, forthwith, hastily, head over heels, headfirst, headforemost, headlong, heels over head, hurriedly, impetuously, implausibly, improbably ... show more.
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