Synonyms : spear carrier, supernumerary

Example : He always carried extras in case of an emergency.

Synonyms : duplicate

Example : Trying to lose excess weight.
Found some extra change lying on the dresser.
Yet another book on heraldry might be thought redundant.
Skills made redundant by technological advance.
Sleeping in the spare room.
Supernumerary ornamentation.
It was supererogatory of her to gloat.
Delete superfluous (or unnecessary) words.
Extra ribs as well as other supernumerary internal parts.
Surplus cheese distributed to the needy.

Synonyms : excess, redundant, spare, supererogatory, superfluous, supernumerary, surplus

Example : A special holiday flight.
Put on special buses for the big game.

Synonyms : special

Example : Called for additional troops.
Need extra help.
An extra pair of shoes.

Synonyms : additional

Example : An extra fast car.