1. (n.) A proponent or advocate; also the power to which a number or variable is raised\; A number, letter, or any quantity written on the right hand of and above another quantity, and denoting how many times the latter is repeated as a factor to produce the power indicated

2. (n.) One who, or that which, stands as an index or representative; as, the leader of a party is the exponent of its principles.

Maecenas abettor admirer advocate aficionado allegorist alter ego alternate amicus curiae angel annotator apologist attorney backer backup backup man booster buff case case in point champion cicerone clarifier commentator critic cross section cryptanalyst cryptographer cryptologist decoder defender definer demonstration demonstrator demythologizer dependence deputy diaskeuast dragoman dummy editor emblem embodiment emendator emender encourager endorser euhemerist example executive officer exegesist exegete exegetist exemplar exemplification explainer explanation explicator expositor expounder fan favorer figurehead friend at court go-between guide hermeneut illustration instance interpreter lexicographer lieutenant locum locum tenens lover mainstay maintainer metaphrast object lesson oneirocritic paranymph paraphrast partisan patron pinch hitter pleader procurator promoter proponent protagonist proxy relevant instance reliance representation representative scholiast second second in command secondary seconder sectary sider specimen sponsor stalwart stand-in standby substitute support supporter surrogate sustainer symbol sympathizer textual critic translator type typical example typification understudy upholder utility man vicar vicar general vice vicegerent votary well-wisher