How to Spell observation

Middle English observacioun "performance (of a religious rite), heeding (of rules, practices)," borrowed from Middle French & Latin; Middle French observacion "act of observing, performance of a prescribed rule," going back to Old French observation "law observed," borrowed from Latin observātiōn-, observātiō "action of watching, adherence (to rules, practices), usage, practice," from observāre "to give attention, watch carefully, abide by" + -tiōn-, -tiō, suffix of verbal action {mat|observe|}