avocation

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An activity taken up in addition to one's regular work or profession, usually for enjoyment; a hobby.

from The Century Dictionary.

• noun The act of calling aside or diverting from some object or employment.
• noun The authoritative removal of a case or process from an inferior to a superior court.
• noun The state of being called, or of wandering aside or away; a diversion of the thoughts.
• noun Hence—4. That which calls one away from one's proper business; a subordinate or occasional occupation; a diversion or distraction.
• noun A person's regular business or occupation; vocation; calling.

from the GNU version of the Collaborative International Dictionary of English.

• noun Obs. or Archaic A calling away; a diversion.
• noun That which calls one away from one's regular employment or vocation.
• noun Pursuits; duties; affairs which occupy one's time; usual employment; vocation.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun obsolete A calling away; a diversion.
• noun A hobby or recreational or leisure pursuit.
• noun That which calls one away from one's regular employment or vocation.
• noun Pursuits; duties; affairs which occupy one's time; usual employment; vocation.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun an auxiliary activity