Conventional \Con*ven"tion*al\, a. [L. conventionalis: cf. F. conventionnel.]

1. Formed by agreement or compact; stipulated.

Conventional services reserved by tenures upon grants, made out of the crown or knights' service. --Sir M. Hale.

2. Growing out of, or depending on, custom or tacit agreement; sanctioned by general concurrence or usage; formal. ``Conventional decorum.'' --Whewell.

The conventional language appropriated to monarchs. --Motley.

The ordinary salutations, and other points of social behavior, are conventional. --Latham.

3. (Fine Arts)
   (a) Based upon tradition, whether religious and historical or of artistic rules.
   (b) Abstracted; removed from close representation of nature by the deliberate selection of what is to be represented and what is to be rejected; as, a conventional flower; a conventional shell. Cf. Conventionalize, v. t.

Source: Webster's Revised Unabridged Dictionary (1913)