One of two parts, give or take
In current English, half is the usual name for one of two parts that make a whole, and also for a part that is only roughly that size. It is a noun in half the work, an adjective in a half share, and an adverb in half open. Speakers stretch it without much fuss: the larger half of an estate, a half smile, measures that are only half serious. Sports use it for one of two playing periods. Clocks use it in half past. In British pubs a half can still mean half a pint.
The origin of the word half is native English. It was not taken from French after the Conquest, and it is not a Latin school word. The history is Germanic from the start, with a twist that modern speakers rarely notice: the oldest English sense was a side or a portion, not a strict fifty-fifty cut.
Inherited, not borrowed
Old English already had the word. West Saxon used healf; Mercian used half and halb. All three parts of speech — noun, adjective, and adverb — are on record in the Old English period, that is before the mid-twelfth century. Standard historical dictionaries treat that as the first known English use, not a later medieval arrival.
The older meaning, a side or a part, did not require equal shares. That reading is still visible in behalf. The noun grew out of Old English phrases that placed someone by another person’s side, or on that person’s side in a dispute. To speak on someone’s behalf is still to stand with them, not to be one of two equal pieces of them. Middle English later mixed the form with a related adverb and preposition meaning near or beside, which is why the modern spelling looks a little detached from half itself.
From Old English the word passed through Middle English half into the present spelling. Scots kept a close cousin, hauf. Nothing in that path looks like a loan; it is ordinary inherited vocabulary moving with the language.
A Germanic stem whose deeper source is unsettled
Behind those English forms sit Proto-West Germanic *halb and Proto-Germanic *halbaz, an adjective meaning half, beside a noun *halbō. The family is easy to see once the dialects are lined up. Dutch has half, German halb, Old Norse halfr, Gothic halbs, Danish, Norwegian, and Swedish halv, West Frisian heal, Icelandic hálfur. Those matches are why the English word is classed as Germanic inheritance rather than a one-off borrowing.
Past that point, specialists do not agree, and it is better to leave the disagreement in view than to force a single story. Some reconstructions attach the Germanic adjective to a Proto-Indo-European root of the *(s)kel- or *(s)kelH- type, with a basic sense of cutting, and then of something divided. Other accounts start from a pre-Germanic *kolp-ó-s whose further origin is simply unclear, and they treat a proposed Sanskrit match as too far in meaning to be safe. A different comparison looks to Lithuanian šalìs, a word for a side or a strip of land, which would fit the old Germanic sense of a side better than a cutting root does. There is also a minority suggestion that the Germanic form was taken from early Finnic, where related words mean cheap or reduced; that remains a hypothesis, not a settled derivation. A substrate origin, with no Indo-European pedigree at all, is another option that serious etymologists leave open.
What is firm is the Germanic layer. What is not firm is everything before it.
Inside English the shape is simple. Half is a root, not a prefix glued to a hidden stem. The related verb is halve. The plural halves shows the same voicing of final f that appears in wife and wives or leaf and leaves. As a combining element, half- later marked kinship that shares only one parent, as in half-brother, and incompleteness, as in half-hearted or half measures. Those compounds are later English habits built on a stem that was already old.
How the meaning tightened, then spread
The central change is a narrowing: from a side or a part to one of two equal parts. The narrowing never quite finished. A joke about the larger half only works because the word can still mean a portion rather than a geometric half. Partial and incomplete uses — half right, half persuaded, not half bad — sit on that same slope. They treat half as less than the full thing, not as a measured fraction.
Old English also used the word in a counting pattern that German still keeps. A phrase such as þridda healf, literally third-half, meant two and a half: one half short of the third unit. The wording two and a half itself is recorded from about 1200. That is a change in how English names mixed numbers, not a change in the word’s core.
Clock language is later still. Half past ten is first attested around 1750. In Scottish usage, as in German halb elf, the half is often named from the hour that is coming rather than the hour that has just gone, so ten-thirty looks forward to eleven. The same small word therefore points backward in one English variety and forward in another.
Specialized senses accumulated without replacing the main one. A half can be a sports period, a British school term, a child fare, a half-dollar in slang, or a liquor measure of twenty-seven gallons in older trade talk. Figurative half-cocked, first used of a firearm whose hammer is only at the first catch, is recorded in that literal sense by the mid-eighteenth century and as a judgment on hasty speech or action in the nineteenth. Those are later English growths. They do not rewrite the Germanic history; they show how freely a short inherited word attracts new jobs.
A cousin in plain sight
German halb and Dutch half still sit next to English half with almost the same form and the same fractional use. That closeness is the simplest proof that the word is home-grown Germanic stock. The more telling fossil, though, is the old sense of a side, which English tucked into behalf while the free word half went on to name a fraction, a clock interval, and anything done only part way.