1660s, "posture or position of a figure in a statue or painting," via French attitude (17c.), from Italian attitudine "disposition, posture," also "aptness, promptitude," from Late Latin aptitudinem (nominative aptitudo; see aptitude, which is its doublet).
Originally 17c. a technical term in art; later generalized to "a posture of the body supposed to imply some mental state" (1725). Sense of "a settled behavior reflecting feeling or opinion" is by 1837. Meaning "habitual mode of regarding" is short for attitude of mind (1757). Connotations of "antagonistic and uncooperative" developed by 1962 in slang.