Vacation, n.
Etymology: [F., fr. L. vacatio a being free from a duty, service, etc., fr. vacare. See Vacate.]
1. The act of vacating; a making void or of no force; as, the vacation of an office or a charter.
2. Intermission of a stated employment, procedure, or office; a period of intermission; rest; leisure. It was not in his nature, however, at least till years had chastened it, to take any vacation from controversy. Palfrey. Hence, specifically: -(a) (Law)
Intermission of judicial proceedings; the space of time between the end of one term and the beginning of the next; nonterm; recess. "With lawyers in the vacation." Shak. (b) The intermission of the regular studies and exercises of an educational institution between terms; holidays; as, the spring vacation. (c) The time when an office is vacant; esp. (Eccl.), the time when a see, or other spiritual dignity, is vacant.
Shades of meaning
Fernald lists vacation only as an antonym, under work.
He lists it without comment; the entries above explain its neighbors.