teoría
/teoˈɾia/ · A2 · noun · f
theory
Greek theoria = a looking-at; same root as theatre, and twin of theory
From Greek theoria, contemplation, built on thea (a viewing), the root that also gives theatre. English theory is the same word: swap the final -y for -ía and stress the í: te-o-RÍ-a. Feminine: la teoría.