Occupation, n.
Etymology: [L. occupatio: cf.F. occupation.]
1. The act or process of occupying or taking possession; actual possession and control; the state of being occupied; a holding or keeping; tenure; use; as, the occupation of lands by a tenant.
2. That which occupies or engages the time and attention; the principal business of one's life; vocation; employment; calling; trade. Absence of occupation is not rest. Cowper. Occupation bridge (Engin.), a bridge connecting the parts of an estate separated by a railroad, a canal, or an ordinary road.
Syn. -- Occupancy; possession; tenure; use; employment; avocation; engagement; vocation; calling; office; trade; profession.
Shades of meaning
Fernald has no entry of its own for occupation; he lists it under business, exercise, work.
Where he writes about it:
A business is what one follows regularly; an occupation is what he happens at any time to be engaged in; trout-fishing may be one's occupation for a time, as a relief from business; business is ordinarily for profit, while the occupation may be a matter of learning, philanthropy, or religion. — from business
Pursuit is an occupation which one follows with ardor. — from business
Trade or trading is, in general, the exchanging of one thing for another; in the special sense, a trade is an occupation involving manual training and skilled labor; as, the ancient Jews held that every boy should learn a trade. — from business
Business, occupation, etc., may be what one does independently; employment may be in the service of another. — from business