c. 1600, "that must be attended, followed, or kept," also "worthy of notice or mention," from Latin observabilis "remarkable, observable," from 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." From 1640s as "perceptible, capable of being observed." Related: Observably; observability.
also discernable, "perceptible, visible, observable," 1560s, from French discernable, from discerner "distinguish (between), separate" (see discern). Form with -a- was more common at first; spelling changed to -i- 17c. to conform to Late Latin discernibilis. Related: Discernibly.
1847, the philosophy, based on actual or absolute knowledge, of Auguste Comte (1798-1857), who published "Philosophie positive" in 1830; see positive (adj.) in the "just the facts" sense + -ism. A philosophy based on positive facts and observable phenomena and abandoning inquiry into causes or ultimate origins. Related: Positivist; Positivistic.
"attack with good-humored jokes and jests," 1670s, origin uncertain; said by Swift to be a word from London street slang. Related: Bantered; bantering. The noun, "good-humored ridicule," is from 1680s.
The third refinement observable in the letter I send you, consists in the choice of certain words invented by some pretty fellows; such as banter, bamboozle, country put, and kidney, as it is there applied; some of which are now struggling for the vogue, and others are in possession of it. I have done my utmost for some years past to stop the progress of mobb and banter, but have been plainly borne down by numbers, and betrayed by those who promised to assist me. [Swift, "The Tatler," No. 230, 1710]