Whereat
Pronunciation : Where*at"
Part of Speech : adv.
Definition : 1. At which; upon which; whereupon; -- used relatively. They vote; whereat his speech he thus renews. Milton. Whereat he was no less angry and ashamed than desirous to obey Zelmane. Sir P. Sidney.
2. At what; -- used interrogatively; as, whereat are you offended
Source : Webster's Unabridged Dictionary, 1913