Observation
late Middle English (in the sense ‘respectful adherence to the requirements of rules or ritual’): from Latin observatio(n- ), from the verb observare (see observe).
wiktionary
From Middle English observacion, borrowed from Middle French observacion. Also a borrowing from French observation and a learned borrowing from Latin observātiō(n-). Morphologically observe + -ation
etymonline
observation (n.)
late 14c., observacioun, "the performance of a religious rite," from Old French observation (c. 1200) and directly from Latin observationem (nominative observatio) "a watching over, observance, investigation," noun of action from past-participle stem of observare "watch over, note, heed, look to, attend to, guard, regard, comply with," from ob "in front of, before" (see ob-) + servare "to watch, keep safe," from PIE root *ser- (1) "to protect." Sense of "act or fact of paying attention" is from 1550s. Meaning "a remark in reference to something observed" is recorded from 1590s.
