guess, presume, surmise, judge, understand
JLPT3 G4 S14 F477
As per 祭# (scrape) + 宀 roof/building → rub a building spotless, eliminating all dirt. *Observe* is an associated meaning (← observe/inspect that which has been cleaned) → *investigate*; *judge*; *estimate*. Also, *be considerate of* and *profound*.
[Full Kanji Etymology List]