specialist

[spesh-uh-list]
noun
  1. a person who devotes himself or herself to one subject or to one particular branch of a subject or pursuit.
  2. a medical practitioner who devotes attention to a particular class of diseases, patients, etc.
  3. U.S. Army. an enlisted person of one of four grades having technical or administrative duties, the grades corresponding to those of corporal through sergeant first class but not requiring the exercise of command.
  4. Stock Exchange. a member of an exchange who executes orders in his or her name or for other stockbrokers in a single stock or a particular group of stocks and thus helps maintain the market in those securities on that exchange.

Origin of specialist

First recorded in 1855–60; special + -ist
Related formsnon·spe·cial·ist, noun, adjectivepre·spe·cial·ist, nounsub·spe·cial·ist, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for subspecialist

specialist

noun
    1. a person who specializes in or devotes himself to a particular area of activity, field of research, etc
    2. (as modifier)specialist knowledge
  1. an enlisted rank in the US Army denoting technical qualifications that entitle the holder to a noncommissioned officer's pay
  2. ecology an organism that has special nutritional requirements and lives in a restricted habitat that provides theseCompare generalist
Derived Formsspecialistic, adjective
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for subspecialist

specialist

n.

1856 (originally in the medical sense); see special + -ist.

Online Etymology Dictionary, © 2010 Douglas Harper

subspecialist in Medicine

specialist

[spĕshə-lĭst]
n.
  1. A physician whose practice is limited to a particular branch of medicine or surgery, especially one who is certified by a board of physicians.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.