D defs.my
Entry 2 senses Webster, 1913

Thereat

· There·at · IPA /ðɛːɹˈæt/
01 adv. At that place; there.
  1. 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. 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.