Head is one of the shortest common nouns in English and one of the most crowded. In ordinary talk it names the part of the body that holds the brain and the main senses. The same form also names a leader, the front of a column, the source of a stream, a unit for counting people or cattle, and the foam on a glass of beer. Those senses look scattered until the history is laid out. English did not borrow this word from French or Latin. It inherited it, then stretched it.
A word English already had
The origin of the word head belongs to the native stock. Old English already used the neuter noun hēafod for the top of the body, the upper end of a slope, a chief person, and a capital town. Middle English shortened the spoken form to hed or heed. The modern spelling with ea is early fifteenth century. At that date the vowel was still long, of the same type as in heat; the spelling stayed after the pronunciation later moved.
One wrinkle in the sound history is worth keeping. The expected modern outcome of the old nominative hēafod would look more like heaved, a two-syllable relic of the extra vowel. The form in use today continues the old oblique stem hēafd-, which lost that syllable. That is why the everyday noun is now a single beat.
This is Germanic inheritance, not a medieval loan. Historical dictionaries place the noun in the Old English period, before 1150, and they record a related verb in the same stretch of time.
Cousins across the North Sea
Old English hēafod comes from Proto-West Germanic *haubud and from Proto-Germanic *haubudą, also reconstructed as *haubidą. The family is easy to see once the later spellings are lined up: Dutch hoofd, German Haupt, Old Frisian haved, Old Saxon forms such as hōƀid, Old Norse hǫfuð (Icelandic höfuð, Swedish huvud, Danish hoved), and Gothic haubiþ.
German Haupt is a useful reminder that a cognate can stay in the language and still lose everyday body-part duty. In modern German the ordinary word for the anatomical head is often Kopf; Haupt survives strongly in compounds and in older or elevated style. English kept the inherited noun as the default term for the body part.
Old English also had a second, less common word for the same anatomy, hafola, from a related Germanic formation *habulô. That rival did not last. Head did.
An older root, and a Latin twin
Handbooks usually take the Germanic noun back to a Proto-Indo-European form reconstructed as *káput-, with the sense head. Latin caput is the best-known sibling. Through French and later learned Latin, English then took in a large set of words built on that same ancient idea: capital, captain, chapter, chief, chef, cape. Those are not children of hēafod. They are doublets. The native line and the borrowed line met again after a long split.
The link between Germanic and Latin is widely accepted. The last stretch of the sound history is not. Some reconstructions start from an earlier Germanic *habudą rather than *haubudą. Many North Germanic dialects keep a vowel that looks closer to that shorter shape, while West Germanic and Gothic show a diphthong. One proposal is metathesis inside an old paradigm that mixed stems. Specialists also note that the first vowel in both *habudą and *habulô is hard to derive from the usual Indo-European rules. The family resemblance stands; the finest grain of the reconstruction does not.
Sanskrit kapāla, a word for skull, is sometimes placed nearby. It is not a straight match for *káput- in the way Latin caput is, so it should not be treated as a clean cognate.
From the body to whatever sits at the top
Old English had already done the semantic work later English would keep doing: treating the head as the highest, foremost, or governing part of a thing. Compounds used hēafod for main long before a separate adjective head, in the sense principal, is recorded around 1200.
The anatomical sense never left. Around it, speakers stacked more pictures of top, front, and source. By the mid-fourteenth century the word could mean the origin of a river. By the late fourteenth it could mean the rounded top of a plant, as in a head of cabbage or lettuce. The obverse of a coin, the side with a portrait, is from the 1680s. Foam on beer is attested by the 1540s. Sailors’ slang for a toilet, from the 1740s, comes from the crew latrine in the bow, the head of the ship.
Synecdoche turned the body part into a person. A head count is recorded from the late thirteenth century. Counting livestock the same way is from the sixteenth. As a measure of height between people the word appears around 1300. Twentieth-century slang added the compound addict sense, as in pothead, from about 1911.
The verb is older than many of those later pictures. The earliest English verb from this root meant to cut off a head: Old English hēafdian. Around 1200 a different verbal use appears, to be at the front or in the lead. To direct one’s course toward something is later, about 1600. Head up in the sense supervise is modern, from around 1930.
One pairing worth keeping
If a single pairing makes the history concrete, set Latin caput beside English head. They are the same ancient word arriving by two roads. One road never left the Germanic household and gave the everyday noun. The other went through Rome and French schooling and gave capital cities, captains, and chapter headings. The body at the top of the spine, the person in charge, and the start of a river were not later poetic add-ons. They were already available in Old English, and they are still the same short word.