professional

Etymology

From Middle English professhennalle, professhynalle; equivalent to profession + -al.

noun

1. A person who belongs to a profession.
2. A person who earns their living from a specified activity.
3. (euphemistic) A prostitute.
   There was this nice lady who flirted with me at the bar, but it turned out that she was a professional.
4. A reputation known by name.
5. An expert.
   I have learned that there is a person attached to a golf club called a professional. Find out who fills that post at the Green Meadow Club; […] invite the professional, urgently, to dine with us this evening. 1934, Rex Stout, Fer-de-Lance, Bantam, published 1992, page 97
6. One of four categories of sociologist propounded by Horowitz: a sociologist who is actively concerned with promoting the profession of sociology.

adj

1. Of, pertaining to, or in accordance with the (usually high) standards of a profession.
   The little green men were clearly professional soldiers by their bearing, carried Russian weapons, and wore Russian combat fatigues, but they had no identifying insignia. Vladimir Putin originally denied they were Russian soldiers; that April, he confirmed they were. 18 March 2019, Steven Pifer, Five years after Crimea’s illegal annexation, the issue is no closer to resolution, The Center for International Security and Cooperation
2. That is carried out for money, especially as a livelihood.
3. (by extension) Expert.