A thinking-place; a place for study.
From Greek phrontisterion; from phrontistes, a thinker; from phroneein, to think
First used by Aristophanes to apply to the school of Socrates, and was somewhat mocking in tone.
Eddie was always getting into trouble at school. When told to be quiet, he would refuse to answer his teacher's questions until he was again given permission to speak; when told off for swearing in religious studies he'd announce that if God didn't want him swearing, he wouldn't have invented swear-words - the final straw and cause for his week long detention was when he was told by his Classical Studies teacher to sit and think about what he had done and he asked to go to the library, as he needed a phrontistery to think!