Antonyms:

idleness,inaction,inactivity,relaxation,rest.

EXPENSE.

Synonyms:

cost,expenditure,outgo,outlay.

The cost of a thing is whatever one surrenders or gives up for it, intentionally or unintentionally, or even unconsciously; expense is what is laid out by calculation or intention. We say, "he won his fame at the cost of his life;" "I know it to my cost;" we speak of a joke at another's expense; at another's cost would seem to make it a more serious matter. There is a tendency to use cost of what we pay for a possession, expense of what we pay for a service; we speak of the cost of goods, the expense of making up. Outlay is used of some definite expenditure, as for the purchase of supplies; outgo of a steady drain or of incidental expenses. See [PRICE].

Antonyms:

gain,proceeds,profit,receipt,return,
income,product,profits,receipts,returns.