Word Origin & History
O.E. half, halb (Mercian), healf (W. Saxon) "side, part" (original sense preserved in behalf), from P.Gmc. *khalbas "something divided" (cf. O.N. halfr, O.Fris., M.Du. half, Ger. halb, Goth. halbs "half"). Used also in O.E. phrases as in modern Ger., to mean "one half unit less than," cf. þridda
healf "two and a half," lit. "half third." The construction in two and a half, etc., is first recorded c.1200. Of time, in half past ten, etc., first attested 1750; in Scottish, the half often is prefixed to the following hour, as in Ger. (halb elf "ten thirty"). Half-and-half "ale and porter" is from 1756; half-baked in sense of "silly" is from 1855; half-breed "mixed race" is from 1760; half-blooded in this sense is from c.1600. Half-brother (early 14c.) and half-sister (c.1200) were in M.E.. Halftime in football is from 1871. half-truth is first recorded 1658; half-hearted is from 1610s. To go off half-cocked "speak or act too hastily" (1833) is in allusion to firearms.
M.E. halfen "to divide in halves," c.1300 (see half