What does fundament mean?
Fundament is a noun with two related senses, one far more current than the other. In modern usage it refers to the buttocks or anus, appearing mostly in medical writing, veterinary contexts, or humorous formal prose where an old-fashioned euphemism is preferred to blunter terms. Its older, now largely obsolete sense denoted a foundation or base — the underlying ground on which something rests, whether a building, an argument, or a body of doctrine. Both senses descend naturally from the word's origin in Latin 'fundamentum', meaning foundation, itself derived from 'fundare', to lay a base. This lineage makes 'fundament' a close cousin of 'foundation' and 'fundamental'. The semantic drift from lofty beginnings to the lowest part of the anatomy gives the word a memorable history: what once named the bedrock of knowledge now names, with dry formality, a considerably less elevated part of the body.
The buttocks or anus.
"The vet examined the animal's fundament for signs of injury."
This is the only sense common today; it reads as formal, clinical, or comically antiquated rather than vulgar.
A base or underlying principle on which something is founded; a foundation.
"He treated scripture as the fundament of his entire argument."
Now rare or archaic, surviving chiefly in theological and philosophical prose.
The plural is rare but straightforward; it appears most often in the archaic 'foundation' sense when discussing multiple bases or principles.
"The treatise examined the fundaments of civil law one by one."
Before it meant your backside, 'fundament' meant the very foundation of all knowledge — the English language quietly demoted it over four centuries of usage.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of fundament
Fundament comes from the Latin 'fundamentum', meaning foundation or bottom, formed from 'fundare' ('to found' or 'lay a base'), which derives ultimately from 'fundus', the bottom of a thing. It entered English via Old French in the Middle Ages, originally carrying the abstract sense of a basis or underlying principle. By around the early seventeenth century, English writers were also applying it anatomically to the buttocks and anus, a sense drawn from Latin medical usage. The same Latin root gave English 'foundation', 'fundamental', 'founder', and 'fund', making these true cognates within the language.
Related word forms
How fundament is actually used
In contemporary English, 'fundament' survives mainly in medical or veterinary contexts and in deliberately formal or comic prose; its anatomical sense carries an old-fashioned, slightly euphemistic tone rather than vulgarity. The older sense meaning 'foundation' is largely obsolete, though it occasionally appears in theological or philosophical writing about underlying principles.
Easily confused with fundament
While 'fundamental' is an adjective meaning basic or essential, 'fundament' is a noun referring either to the buttocks or, archaically, to a foundation.