on spec

Describes work, such as advertising that is done for a client without a contract or job order, for which the client will pay only if the work is to be used. When a job is done on speculation, the person doing the work takes the risk in the hope of making a profit, gaining a valuable credit, or for some other reason. In the advertising business, creative talent will often work on spec in order to establish a name in the industry.

Describes work, such as advertising, that is done for a client without a contract or job order, for which the client will pay only if the work is to be used.

Done on a speculative basis; with no assurance of profit. For example, We didn't design our house; the builder built it on spec. The use of spec as an abbreviation for speculation dates from the late 1700s.