(n.) Having a tendency to flop or flap; as, a floppy hat brim.

anemic asthenic bagging baggy ballooning bloodless chicken cowardly debilitated drooping droopy dull effete etiolated faint faintish feeble flabby flaccid flimsy gone gutless imbecile impotent languid languorous lax limber limp listless loose lop lop-eared loppy lustless marrowless nerveless nodding pithless pooped powerless relaxed rubbery sagging sagging in folds saggy sapless sinewless slack sleazy soft spineless strengthless swag unhardened unnerved unstrung weak weakly