amateur and professional.

Amateur:
n.

1. A person who engages in an art, science, study, or athletic activity as a pastime rather than as a profession.
2. Sports. An athlete who has never accepted money, or who accepts money under restrictions specified by a regulatory body, for participating in a competition.
3. One lacking the skill of a professional, as in an art.

adj.

1. Of or performed by an amateur.
2. Made up of amateurs: an amateur cast.
3. Not professional; unskillful.

[French, from Latin amātor, lover, from amāre, to love.]

amateurism am'a·teur·ism n.

SYNONYMS amateur, dabbler, dilettante. These nouns mean one engaging in a pursuit but lacking professional skill: a musician who is a gifted amateur, not a professional; a dabbler in the stock market; a sculptor but a mere dilettante.
ANTONYM professional

WORD HISTORY When Mrs. T.W. Atkinson remarked in her 1863 Recollections of the Tartar Steppes and their Inhabitants, "I am no amateur of these melons," she used amateur in a sense unfamiliar to us. That sense, "a lover, an admirer," is, however, clearly descended from the senses of the word's ultimate Latin source, amātor, "lover, devoted friend, devotee, enthusiastic pursuer of an objective," and from its Latin-derived French source, amateur, with a similar range of meanings. First recorded in English in 1784 with the sense in which Mrs. Atkinson used it, amateur is found in 1786 with a meaning more familiar to us, "a person who engages in an art, for example, as a pastime rather than as a profession," a sense that had already developed in French. Given the limitations of doing something as an amateur, it is not surprising that the word is soon after recorded in the disparaging sense we still use to refer to someone who lacks professional skill or ease in performance.

Professional

adj.

1. 1. Of, relating to, engaged in, or suitable for a profession: lawyers, doctors, and other professional people.
   2. Conforming to the standards of a profession: professional behavior.
2. Engaging in a given activity as a source of livelihood or as a career: a professional writer.
3. Performed by persons receiving pay: professional football.
4. Having or showing great skill; expert: a professional repair job.

n.

1. A person following a profession, especially a learned profession.
2. One who earns a living in a given or implied occupation: hired a professional to decorate the house.
3. A skilled practitioner; an expert.