Source : Webster's Revised Unabridged Dictionary (1913)

Thereat \There*at"\, adv.
   1. At that place; there.

            Wide is the gate, and broad is the way, that leadeth
            to destruction, and many there be which go in
            thereat.                              --Matt. vii.
                                                  13.

   2. At that occurrence or event; on that account.

            Every error is a stain to the beauty of nature; for
            which cause it blusheth thereat.      --Hooker.