In the beginning, it literally meant a brick being used as a projectile. Now, ‘brickbat’ just means insults

Brickbat (noun), an unfavourable criticism, unkind remark or sharp put-down

Usage: The politician‘s performance in his constituency merited the several brickbats thrown at him by his critics.

As one can imagine, the word “brickbat” began its innings literally rather than metaphorically in the mid-16th century, describing a piece of brick (half a brick or less, but always, according to purists, retaining one unbroken end of the brick) used as a handy projectile, especially where stones were scarce, to throw at people one disapproved of. The word comes, of course, from the words brick and bat, the latter in the sense of a lump, or a piece (I know we think of a bat as a club we wield in cricket, but the “lump” meaning still exists, as in the lumps of cotton wadding used in quilts that are still called “batting”).

But soon enough the literal sense gave way to the figurative, so that rather than using a brickbat as a missile, it began to refer to comments, insults, and the like. By 1642, the poet John Milton was using the word in a figurative sense to mean an uncomplimentary remark or a harsh criticism (“I beseech ye friends, ere the brick-bats flye, resolve me and yourselves…”). Literary and theatre critics are particularly fond of flinging brickbats at the works and writers they don’t think highly of, and doing so literally might land them in jail, so brickbat-as-metaphor is the usage we usually come across.

In this sense a brickbat is more nasty than a mere negative word; its use implies an insult hurled at a target with an intent to wound, and therefore can only be applied to extremely blunt criticism. It is often mated with its contrasting opposite, “bouquet” — as in, “Poor Shashi Tharoor has both bouquets and brickbats showered on his head daily for anything he says!” This is a 20th century usage that may have faded with that century, because one comes across the pair far less often than one sees brickbats flying by themselves. Perhaps we are just an unkinder species now!

Some of you will recall the adage “bricks and stones may break my bones, but words can never hurt me.” Whoever said that, and the many who thought it wise enough to pass it down over the generations as a proverb worth citing, needs to have a brickbat thrown at them. A broken bone heals far more quickly and durably than the emotional and psychic injuries inflicted by a savage word, which is where the brickbat derives its power. The many libel and defamation suits that litter the courts show that the figurative brickbat hurts just as much as, if not more than, the literal one. The pen may or may not be mightier than the sword, but it can indeed be as painful an offensive weapon as the brickbat.