c. 1200, "better than ordinary," from Old French special, especial "special, particular, unusual" (12c., Modern French spécial) and directly from Latin specialis "individual, particular" (source also of Spanish especial, Italian speziale), from species "appearance, kind, sort" (see species).
Meaning "marked off from others by some distinguishing quality" is recorded from c. 1300; that of "limited as to function, operation, or purpose" is from 14c. Special effects first attested 1951. Special interests in U.S. political sense is from 1910. Special pleading first recorded 1680s, a term that had a sound legal meaning once but now is used generally and imprecisely. Special education in reference to those whose learning is impeded by some mental or physical handicap is from 1972.