Word Origin & History
late 14c., "to hold to" (a manner of life or course of conduct), from O.Fr. observer, from L. observare "watch over, look to, attend to, guard," from ob "over" + servare "to watch, keep safe," from PIE base *ser- "to protect." Meaning "to attend to in practice, to keep, follow" is attested from late
14c. Sense of "watch, perceive, notice" is c.1560, via notion of "see and note omens." Meaning "to say by way of remark" is from c.1600.
1612, from un-
(1) "not" + pp. of observe