The Collaborative International Dictionary of English v.0.48:
Reverter \Re*vert"er\, n. 1. One who, or that which, reverts. [1913 Webster] 2. (Law) Reversion. --Burrill. [1913 Webster]Bouvier's Law Dictionary, Revised 6th Ed (1856):
REVERTER. Reversion. A formedon in reverter is a writ which was a proper remedy when the donee in tail or issue died without issue and a stranger abated: or they who were seised by force of the entail discontinued the same. Bac. Ab. Formedon, A 3.