a person who belongs to a group or organization, esp. a political one, that is or is presumed to be a cover or disguise for another activity
a Communist fronter
Word origin
[front + -er1]-er is a suffix used in forming nouns designating persons from the object of their occupationor labor (hatter; tiler; tinner; moonshiner), or from their place of origin or abode (Icelander; southerner; villager), or designating either persons or things from some special characteristic or circumstance(six-footer; three-master; teetotaler; fiver; tenner)