Definition of "flail" []

• A manual threshing device consisting of a long wooden handle or staff and a shorter, free-swinging stick attached to its end. (noun)
• To beat or strike with or as if with a flail: flailed our horses with the reins. (verb-transitive)
• To wave or swing vigorously; thrash: flailed my arms to get their attention. (verb-transitive)
• To thresh using a flail. (verb-transitive)
• To move vigorously or erratically; thrash about: arms flailing helplessly in the water. (verb-intransitive)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The Army wanted a robot that could perform a task called "flail" - essentially tilling dirt to find bombs buried beneath, and then either disabling or detonating them without destroying the robot."
• "I am indulgent on this, I suppose: it won’t do them any good in the long-term, watching them flail is amusing, and they’ll probably cut something that will seriously annoy their base support."
• "When we thresh our corn, the flail is the final cause of the separation of the grain."