masc. proper name, also Charley, familiar form of Charles (also see -y (3)); 1965 in Vietnam War U.S. military slang for "Vietcong, Vietcong soldier," probably suggested by Victor Charlie, military communication code for V.C. (as abbreviation of Viet Cong), perhaps strengthened by World War II slang use of Charlie for Japanese soldiers, which itself is probably an extension of the 1930s derogatory application of Charlie to any Asian man, from fictional Chinese detective Charlie Chan.
Other applications include "a London night watchman" (1812); "a goatee beard" (1834, from portraits of King Charles I and his contemporaries); "a fox" (1857); in plural "a woman's breasts" (1874); "an infantryman's pack" (World War I); and "a white man" (Mr. Charlie), 1960, American English, from African-American vernacular.
1590s, "one who copulates," agent noun from fuck (v.). By 1893 as a general term of abuse (or admiration).
DUCK F-CK-R. The man who has the care of the poultry on board a ſhip of war. ["Classical Dictionary of the Vulgar Tongue," 1796]
1660s, "private man of war, armed vessel owned and officered by private persons, usually acting under commission from the state," from private (adj.), probably on model of volunteer (n.), buccaneer. From 1670s as "one commanding or serving on a privateer." As a verb, 1660s (implied in privateering) "to cruise on a privateer, to seize or annoy an enemy's ships and commerce."