† obserˈvatical,a.Obs.rare—1. [irreg.f. L. observāt-us observation + -ical.] Of or pertaining to (scientific) observation; observational. 1703T. S. Art's Improv. p. iv, A Compleat Experimental, and Observatical History, will be of great use to Anticipate the loss of many rare and useful Experiments, Inventions and Arts.