Fictio

Fictio is a Latin noun meaning feigning, invention, or something made up; in a broader sense it can refer to fiction or falsehood. It is derived from fingere, to shape or feign, and the word is feminine with the typical 3rd‑declension form fictio, fictionis.

In classical usage, fictio denotes the act of feigning or the result of feigning—an invented account, a hypothetical claim, or a crafted story. The term appears in discussions of rhetoric, philosophy, and argumentation to describe devices that present something as if it were true, even when it is not.

In Roman law and later legal theory, fictio often appears as a technical term for a legal fiction—an assumption treated as true for purposes of the law to achieve a particular legal effect. An example is fictio iuris, where a legal construct allows a rule to operate under a premise that may be factually inaccurate.

In literary and scholarly contexts, fictio may be used to discuss fiction more generally, though Latin authors more commonly employ terms such as fabula or narratio to refer to a story or account. The concept, however, has influenced later vocabulary; the modern word fiction in English and many Romance languages traces its semantic lineage back to fictio.

Today, fictio survives primarily as a term of philology, linguistics, and historical studies. It appears in dictionaries and commentaries on Latin rhetoric, law, and literature, where it helps distinguish feigned or invented content from factual statement.