Definition "ex" in Collins English Dictionary & Thesaurus, spelling "ex"

ex  (exes plural )Someone's ex is the person they used to be married to or used to have a romantic or sexual relationship with.
INFORMAL  n-count usu poss N
He's different from my ex., ...one of her exes.

ex-
ex- is added to nouns to show that someone or something is no longer the thing referred to by that noun. For example, a woman's ex-husband is no longer her husband.  prefix
...my ex-wife., ...ex-President Reagan., ...an ex-soldier.

ex-directory
If a person or their telephone number is ex-directory, the number is not listed in the telephone directory, and the telephone company will not give it to people who ask for it.
(BRIT)  adj
in AM, use unlisted

ex gratia
An ex gratia payment is one that is given as a favour or gift and not because it is legally necessary.
(mainly BRIT)
FORMAL adj usu ADJ n

ex officio
Ex officio is used to describe something such as a rank or privilege that someone is entitled to because of the job or position they have.
FORMAL  adj ADJ n
...ex officio members of the Advisory Council., ...an ex-officio degree.

ex-serviceman   (ex-servicemen plural )An ex-serviceman is a man who used to be in a country's army, navy, or air force.
(BRIT)  n-count
in AM, use veteran