What does fornicate mean?
Fornicate is a verb referring to sexual intercourse, classically defined as intercourse between partners who are not married to each other. Rooted in centuries of religious and legal doctrine, the word carries a formal, often judgmental tone that sets it apart from neutral everyday language. It appears most frequently in theological writings, historical court records, and discussions of morality, where it denotes the specific offense of illicit sex rather than intimacy in general. The term derives from the Latin fornix — an arch or vault — a link to the arched cellars of ancient brothels that gave the practice its name. Though largely absent from casual conversation, where blunter synonyms dominate, "fornicate" remains useful for readers of older literature, legal history, and religious texts, and it survives as a precise, if solemn, label for a concept that many other words blur.
To engage in sexual intercourse, especially outside of marriage.
"Historical sermons admonished congregants not to fornicate before wedlock."
A person who engages in fornication; a fornicator.
"The old statute listed fines levied against known fornicators."
This noun form is usually expressed by the derivative "fornicator" rather than by using "fornicate" itself as a noun.
The word "fornicate" traces back to Latin "fornix," meaning an arch or vault — the word for a brothel's arched cellar, which is how the sexual sense got its name.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of fornicate
The English verb derives from Late Latin "fornicari," meaning to have illicit intercourse, itself rooted in "fornix," the Latin term for an arch or vaulted space — notably the underground passages of Roman brothels. The word entered English in the late medieval period through ecclesiastical and legal usage, retaining its association with unlawful or sinful sex. Cognates such as "fornication" (the noun) and "fornicator" developed directly from the same stem, and related Romance-language terms share the same Latin ancestry.
Related word forms
How fornicate is actually used
Largely formal, legal, or religious in register today; colloquial English has largely replaced it with less loaded terms. In many jurisdictions it no longer carries legal consequences, but its moral and religious connotations persist, especially in traditional Christian discourse.
Easily confused with fornicate
"Fornicate" is the verb describing the act itself, while "fornication" is the noun denoting the act or the offense as a concept or charge.