"U.S. Marine," 1914, Navy slang, from leather + neck (n.). So called for the leather collars of their early uniforms; earlier in British use (1890) it was a sailor's term for a soldier.
Entries linking to leatherneck
leather n.
Old English leðer (only in compounds) "tanned or otherwise dressed hide or skin of an animal," from Proto-Germanic *lethran (source also of Old Norse leðr, Old Frisian lether, Old Saxon lethar, Middle Dutch, Dutch leder, Old High German ledar, German Leder), from PIE *letro- "leather" (source also of Old Irish lethar, Welsh lledr, Breton lezr). As an adjective from early 14c.; it acquired a secondary sense of "sado-masochistic" 1980s, having achieved that status in homosexual jargon in the 1970s.
In commercial and popular usage leather does not include skins dressed with the hair or fur on: such skins are usually distinguished by compounding the word skin with the name of the animal from which they are taken: as sealskin, bearskin, otter skin, etc. In the untanned state skins valued for their fur, hair, or wool and destined to be tawed and dressed for furriers' and analogous uses, are called pelts or peltry. [Century Dictionary, 1900]
neck n.
"that part of an animal body between the head and the trunk and which connects those parts," Middle English nekke, from Old English hnecca "neck, nape, back of the neck" (a fairly rare word) from Proto-Germanic *hnekk- "the nape of the neck" (source also of Old Frisian hnekka, Middle Dutch necke, Dutch nek, Old Norse hnakkr, Old High German hnach, German Nacken "neck"), with no certain cognates outside Germanic, though Klein's sources suggest PIE *knok- "high point, ridge" (source of Old Irish cnocc, Welsh cnwch, Old Breton cnoch "hill").
The more usual Old English words were hals (the general Germanic word, cognate with Gothic, Old Norse, Danish, Swedish, Dutch, German hals), from Proto-Germanic *halsaz, which is perhaps cognate with Latin collum (see collar (n.)); and sweora, swira "neck, nape," probably also from a PIE root meaning "column" (cognate with Old English swer "column," Sanskrit svaru- "post").
Oxen and other draught animals being yoked by the neck, it became a symbol of burdens, of submission or subjugation, and also resistance or obstinacy (compare stiff-necked). Figuratively, "life" (late 15c.) from the breaking or severing of the neck in legal executions. Meaning "narrow part at the top of a bottle" is from late 14c.; meaning "part of a garment which covers the neck" is from 1520s. Meaning "long, slender part of a stringed musical instrument" is from 1610s.
Sense of "isthmus, long, narrow strip of land connecting two larger ones" is from 1550s. Phrase neck of the woods (American English) is attested from 1780 in the sense of "narrow stretch of woods;" 1839 with meaning "settlement in a wooded region." To stick (one's) neck out "take a risk" is recorded by 1919, American English. Horses running neck and neck "at an equal pace" is attested from 1799; to win by a neck is from 1823. To be up to the neck "have a lot of" at first (mid-19c.) suggested "fed full," but since c. 1900 it has implied "in deep."