ex·tra / ˈekstrə/ • adj. added to an existing or usual amount or number: they offered him an extra thirty-five cents an hour.• adv. 1. to a greater extent than usual; especially: he is trying to be extra good.2. in addition: installation will cost about $60 extra.• n. an item in addition to what is usual or strictly necessary: I had an education with all the extras. ∎  an item for which an additional charge is made: the price you pay includes all major charges—there are no hidden extras. ∎  a person engaged temporarily to fill out a scene in a movie or play, esp. as one of a crowd. ∎ dated a special issue of a newspaper.

EXTRA

[Latin, Beyond, except, without, out of, outside.] Additional.

An extra in a contract would include anything outside of, beyond, or not called for by the contract, such as additional materials.

Extra

A paranormally imposed face or figure on a photographic film or plate. Such extras were alleged to appear on pictures produced through psychic photography and spirit photography.

extra that is beyond the usual XVIII; adv., sb. XIX. prob. short for EXTRAORDINARY.