backup (n.)

• about-face
• advocate
• agent
• alternate
• alternative
• analogy
• attorney
• backing
• champion
• change
• changeling
• comparison
• copy
• counterfeit
• deputy
• double
• dummy
• equal
• equivalent
• ersatz
• exchange
• exponent
• fake
• figurehead
• fill-in
• ghost
• ghostwriter
• imitation
• lieutenant
• locum
• makeshift
• metaphor
• metonymy
• mock
• personnel
• phony
• pinch
• pleader
• procurator
• proxy
• relief
• replacement
• representative
• reserve
• reserves
• reversal
• reverse
• reversion
• ringer
• secondary
• sign
• spare
• stand-in
• stopgap
• sub
• substitute
• substitution
• succedaneum
• supplanter
• surrogate
• symbol
• synecdoche
• temporary
• token
• turnabout
• turnaround
• understudy
• utility
• vicar
• vice
• vice-regent
• vicegerent
• volte-face