"flail" in the noun sense
an implement consisting of handle with a free swinging stick at the end used in manual threshing
"flail" in the verb sense
1. thrash, thresh, lam, flail
give a thrashing to beat hard
2. flail, thresh
move like a flail thresh about
"Her arms were flailing"
Source: WordNet® (An amazing lexical database of English)
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