also: ぱっとみ
noun
at a glance; from appearances
Casual expression used when making a quick judgment based on first sight or surface impression. Often used adverbially as パッと見(で).
パッと見は簡単そうだけど、実は難しい問題だ。
At a glance it looks easy, but it's actually a difficult problem.
パッと見で彼が外国人だとわかった。
I could tell at a glance that he was a foreigner.
見た目 refers to outward appearance itself, whereas パッと見 emphasizes the quick, first-impression judgment.
Combination of the mimetic adverb パッと (suddenly, quickly) and 見 (seeing). The exact origin is uncertain, but it likely arose as a colloquial expression for a quick visual impression.