On Meanings and Change
"The word study is based on Latin studium which meant "painstaking application" or "zeal, eagerness," and was related to Latin studere "to be zealous." Student, studio, and studious all share this base. Study's earliest uses are surprising: "affection, friendliness" (again, by Chaucer, c 1374), an "occupation or pursuit," and "a state of reverie or abstraction; state of perplexity." Soon, though, it was used to mean thought or effort that was applied toward the accomplishment of a purpose."