Tertius

Part of speech: adjective, noun

Definitions

1. A term referring to a third party or participant in a situation
2. denoting a third option or alternative in a decision-making process
3. used in legal contexts to describe someone not directly involved in a particular matter

Etymology: The Latin "tertius" simply means "third," from "tres" (three) with the ordinal ending, so it has been a number word since antiquity. English picked it up mainly as a technical and legal term. The most common modern use is in "tertius gaudens," the Latin phrase meaning "the third who rejoices," which describes someone who profits from a quarrel between two others without taking part in it. The sociologist Georg Simmel discussed this figure in his writing on social forms in the early twentieth century, and the phrase has been used in English ever since. The adjective sense "not directly involved" comes from that idea of a third party standing apart from a dispute. In everyday English the word is rarely used alone, so it survives mostly in this phrase and in the Latin-derived terminology of law and logic, where a "tertius" is an outsider to a transaction or lawsuit.

Synonyms: third

Antonyms: first, second