substitute
sub-sti-tute
verb
To use or put someone or something in place of another.
"You can substitute honey for sugar in this recipe."
noun
A person or thing that takes the place of another, often temporarily.
"The manager brought on a substitute."
Thesaurus
Synonyms: alternative, alternate, secondary, fill in, stand in, sub, second-stringer, reserve, replacement, deputize, step in, deputise