thereat

Adverb

there=at

CIDE DICTIONARY

thereat, adv.

At that place; there. [1913 Webster]
"Wide is the gate, and broad is the way, that leadeth to destruction, and many there be which go in thereat." [1913 Webster]
At that occurrence or event; on that account. [1913 Webster]
"Every error is a stain to the beauty of nature; for which cause it blusheth thereat." [1913 Webster]

thereat, adv. archaic 1 at that place.
2 on that account.
3 after that.