"woman, girl," by 1991, from dude in the surfer/teen slang sense + fem. ending -ette. Earlier (in the fastidious dresser/Old West sense) were dudine (1883), dudess (1885).
Entries linking to dudette
dude n.
1883, "fastidious man," New York City slang of unknown origin; recent research suggests it is a shortening of Yankee Doodle, based on the song's notion of "foppish, over-fastidious male" (compare macaroni). The vogue word of 1883, originally used in reference to the devotees of the "aesthetic" craze, later applied to city slickers, especially Easterners vacationing in the West (as in dude ranch "ranch which entertains guests and tourists for pay," attested by 1921). "The term has no antecedent record, and is prob. merely one of the spontaneous products of popular slang" [Century Dictionary].
Now, "tenderfoot" is not to be construed as the Western equivalent of that much evolved and more abused specimen of mankind, familiarly styled "dude." For even the Montana cowboy recognizes the latter. Not that he has ever seen the true prototype of a that was erstwhile so numerous among us. But he is convinced that a person caught in the act of wearing a white linen collar, and who looks as though he might have recently shaved or washed his face, must be a dude, true and proper. ["Random Notes and Observations of a Trip through the Great Northwest," The Medical Record, Oct. 20, 1883]
Application to any male is recorded by 1966, U.S., originally in African-American vernacular.
DUDE: This does not mean "tenderfoot," as it once did. It now is used to refer positively to somebody. "Charlie's a nice dude." Occasionally it's used as a neutral noun, so you can call someone a "strange dude." [Mike Jahn, "Are You Hip?" Louisville, Ky. Courier-Journal, July 11, 1971]
-ette
diminutive word-forming element, from Old French -ette (fem.), used indiscriminately in Old French with masculine form -et (see -et). As a general rule, older words borrowed from French have -et in English, while ones taken in since 17c. have -ette. In use with native words since late 19c., especially among persons who coin new product names, who tend to give it a sense of "imitation, a sort of" (for example flannelette "imitation flannel of cotton," 1876; leatherette, 1855; linenette, 1894). Also in such words as lecturette (1867), sermonette, which, OED remarks, "can scarcely be said to be in good use, though often met with in newspapers."