JACKLEG

Etymology

Compare blackleg (a person who replaces striking workers; a cheater) and such expressions as jack of all trades, every man jack.

Adjective

jackleg (not comparable)

(US) Amateur, untrained; incompetent.

(US) Dishonest, unscrupulous.

(US) Ineptly built or operated; makeshift.

Noun

jackleg (plural jacklegs)

A type of drill operated by means of compressed air.

(US) An amateur; an untrained or incompetent person.

(US) A shyster or con artist; a gambler who cheats; a generally dishonest or reprehensible person.

Usage notes

Although the term most often carries negative connotations (inept, dishonest), it may also have positive ones (self-taught expert, hands-on learner). Occasionally it is used as a generic pejorative intensifier, equivalent to damn, out-and-out, etc, e.g. a jackleg crook, a jackleg bastard.

Source: Wiktionary