What does ex mean?
Ex is an informal noun referring to a person's former husband, wife, boyfriend, girlfriend, or partner. It arose as a clipped form of expressions like ex-wife and ex-husband, where the prefix ex- comes from Latin, meaning 'out of' or 'formerly'. In modern usage, saying 'my ex' instantly communicates that a past romantic relationship exists without needing further detail, which has made the word ubiquitous in conversation, pop music, and social media. Beyond romance, ex- also functions productively as a prefix attached to titles and roles—ex-president, ex-athlete, ex-employee—to signal that someone no longer holds that position. The standalone noun carries a casual register and often implies some emotional history or unresolved feeling, while prefixed uses remain neutral and factual. Its brevity and emotional resonance have made it one of the most recognizable short words in contemporary English.
Informal term for a former spouse or romantic partner.
"She met her ex for coffee to return his belongings."
Always used informally; usually preceded by a possessive ('my ex', 'her ex').
Combining form indicating that a person formerly held the role named, as in ex-husband, ex-president, or ex-smoker.
"An ex-employee filed a complaint about workplace conditions."
Standard plural, used informally when referring to more than one former partner.
"They swapped stories about their exes over dinner."
The 'ex' in ex-girlfriend comes straight from Latin ex-, meaning 'out of' — so an ex is literally someone you are now 'out of' a relationship with.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of ex
Ex derives ultimately from Latin ex-, meaning 'out of' or 'from', which appears in countless English borrowings such as exit, export, and extract. English adopted ex- as a productive prefix indicating former status, seen in words like ex-king and ex-convict from the early modern period onward. The informal noun use, meaning a former romantic partner, developed in the 20th century by clipping longer forms such as ex-wife or ex-boyfriend, becoming widespread in American and British speech by the late 20th century.
Related word forms
How ex is actually used
Highly informal when used alone for a person ('my ex'); neutral and widely accepted when used as a prefix attached to another noun (ex-boss, ex-colleague). Common in everyday speech across British and American English.
Easily confused with ex
'Axe' is a tool for chopping or, informally, to dismiss someone, while 'ex' refers to a former partner or denotes a former status.