See brickbat in American Heritage Dictionary 4
Origin: + bat1, piece of brick. Word History: The earliest sense of brickbat, first recorded in 1563, was “a piece of brick.” Such pieces of brick have not infrequently been thrown at others in the hope of injuring them; hence, the figurative brickbats (first recorded in 1929) that critics hurl at performances they dislike. The appearance of bat as the second part of this compound is explained by the fact that the word bat, “war club, cudgel,” developed in Middle English the sense “chunk, clod, wad,” and in the 16th century came to be used specifically for a piece of brick that was unbroken on one end.
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