The Collaborative International Dictionary of English v.0.48:
Thereto \There*to"\, adv. 1. To that or this. --Chaucer. [1913 Webster] 2. Besides; moreover. [Obs.] --Spenser. [1913 Webster] Her mouth full small, and thereto soft and red. --Chaucer. [1913 Webster]WordNet (r) 3.0 (2006):
thereto adv 1: to that; "with all the appurtenances fitting thereto" [syn: thereto, to it, to that]