alternate
n. countablen. a person or thing that takes the place of another. You use this when the first choice is not available or when people take turns doing a job.
n. a person or thing that acts as a substitute or replacement for another. Often used in professional or formal contexts to describe a backup representative or a secondary option.
We have an alternate ready if the lead singer gets sick.
The committee appointed an alternate to attend the conference in case the primary delegate was delayed by travel issues.
In high-stakes orchestral performances, an alternate must remain as prepared as the principal player, ready to step in at a moment's notice without any drop in technical quality.
Borrowed from Latin alternātus, the perfect passive participle of Latin alternō (“to take turns”) (see -ate (1,2 and 3)), from alternus (“one after another, by turns”), from alter (“other”) + -nus. Doublet of altern; see also alter.
Commonly used in American English where British English might prefer 'alternative' for a person filling a role.
He is the alternative for the roleHe is the alternate for the roleIn the context of a backup person, 'alternate' is the specific noun; 'alternative' usually refers to one of two or more available possibilities.