understudy (n.)
- advocate
- agent
- alternate
- alternative
- analogy
- attorney
- backup
- champion
- change
- changeling
- commission
- comparison
- copy
- counterfeit
- deputy
- double
- dummy
- equal
- equivalent
- ersatz
- exchange
- exponent
- extra
- fake
- figurehead
- fill-in
- ghost
- ghostwriter
- imitation
- lieutenant
- locum
- makeshift
- metaphor
- metonymy
- mute
- personnel
- phony
- pleader
- procurator
- proxy
- relief
- replace
- replacement
- representative
- reserve
- reserves
- ringer
- second
- secondary
- sign
- spell
- stand-in
- standby
- sub
- substitute
- substitution
- succedaneum
- super
- supernumerary
- supplanter
- support
- surrogate
- symbol
- synecdoche
- token
- vicar
- vice
- vice-regent
- vicegerent
- walk-on
