One who is devoted to a particular occupation or branch of study or research: "Specialists . . . tend to think in grooves"(Elaine Morgan).
A physician whose practice is limited to a particular branch of medicine or surgery, especially one who is certified by a board of physicians: a specialist in oncology.
Any of several noncommissioned ranks in the U.S. Army that correspond to that of corporal through sergeant first class.
[spesh-uh-lis-tik] 
əˈlɪs