Below, contrary to, or failing to meet the standards expected in a particular profession; esp. improper or inappropriate in a professional context.

depreciative. Done in an inept or unskilful way; incompetent; inexpert.

(un-, prefix1 affix 1c.)

Characteristic of an amateur; unskilful, inexpert.

Resembling or having the character of a hack writer or hack writing; amateurish; hackneyed.

(un-, prefix1 affix 6c.)

Of or belonging to an amateur night; (now chiefly) resembling or characteristic of an amateur night; inept, amateurish, disorganized and chaotic.

(a) n. (on radio, television, etc.) a time slot in which amateur entertainers perform; (also in extended use) a period characterized by a lack of…

In extended use: produced or performed by a non-specialist or an unqualified person; amateur; impromptu. Cf. DIY, adj. 2.

= do-it-yourself, adj. 2.