"demonstrable proposition in science or mathematics," 1550s, from Middle French théorème (16c.) and directly from Late Latin theorema, from Greek theorema "spectacle, sight," in Euclid "proposition to be proved," literally "that which is looked at," from theorein "to look at, behold" (see theory).

theological

theologist

theology

theophany

Theophilus

theorem

theoretical

theorist

theorize

theory

theosophy