baldhead (n.)

c. 1300, ballede, "wanting hair in some part where it naturally grows," of uncertain origin. Perhaps with Middle English -ede adjectival suffix, from Celtic bal "white patch, blaze" especially on the head of a horse or other animal (from PIE root *bhel- (1) "to shine, flash, gleam").

Compare, from the same root, Sanskrit bhalam "brightness, forehead," Greek phalos "white," Latin fulcia "coot" (so called for the white patch on its head), Albanian bale "forehead." But connection with ball (n.1), on notion of "smooth, round" also has been suggested, and if not formed from it it was early associated with it. Middle English Compendium says it probably was formed on the root of ball, and compares Old Danish bældet.

Sometimes figurative: "meager" (14c.), "without ornament" (16c.), "open, undisguised" (19c.). Of automobile tires with worn treads, by 1930. Bald eagle is attested by 1680s; so called for its white head.

Old English heafod "top of the body," also "upper end of a slope," also "chief person, leader, ruler; capital city," from Proto-Germanic *haubid (source also of Old Saxon hobid, Old Norse hofuð, Old Frisian haved, Middle Dutch hovet, Dutch hoofd, Old High German houbit, German Haupt, Gothic haubiþ "head"), from PIE root *kaput- "head."

Modern spelling is early 15c., representing what was then a long vowel (as in heat) and remained after pronunciation shifted. Of rounded tops of plants from late 14c. Meaning "origin of a river" is mid-14c. Meaning "obverse of a coin" (the side with the portrait) is from 1680s; meaning "foam on a mug of beer" is first attested 1540s; meaning "toilet" is from 1748, based on location of crew toilet in the bow (or head) of a ship.

Synechdochic use for "person" (as in head count) is first attested late 13c.; of cattle, etc., in this sense from 1510s. As a height measure of persons, from c. 1300. Meaning "drug addict" (usually in a compound with the preferred drug as the first element) is from 1911.

To be over (one's) head "beyond one's comprehension" is by 1620s. To give head "perform fellatio" is from 1950s. Phrase heads will roll "people will be punished" (1930) translates Adolf Hitler. Head case "eccentric or insane person" is from 1966. Head game "mental manipulation" attested by 1972.