What does it mean to feel fluttered?

admirable, adorable, alluring, angelic, appealing, beauteous, bewitching, captivating, charming, classy, comely, cute, dazzling, delicate, delightful, divine, elegant, enthralling, enticing, excellent, exquisite, fair, fascinating, fetching, fine, foxy, good-looking, gorgeous, graceful, grand, handsome, ideal, inviting …

Verb. Opposite of past tense for to move or cause to move in a rhythmic, flapping motion. calmed . remained . soothed .

: a quick wavering or flapping movement or sensation felt a fluttering in his stomach That’s about as small as the perturbation of air produced by the fluttering of a butterfly’s wings …— Gary Taubes.