late 14c., marcien "of, pertaining to, or characteristic of the planet Mars" (originally in reference to astrological influence), from Latin Martius "sacred to (the god) Mars; pertaining to (the planet) Mars," from Mars (genitive Martis; see Mars). From mid-15c. as "of or pertaining to the god Mars, warlike;" also sometimes "of or pertaining to the month of March" (1620s). The noun meaning "an inhabitant of the planet Mars" is attested by 1877.
late 14c., "warlike, of or pertaining to war," from Medieval Latin martialis "of Mars or war," from Latin Mars (genitive Martis), Roman god of war (see Mars). The sense of "connected with military organizations" (opposed to civil) is from late 15c. and survives in court-martial. Also, occasionally (with a capital M-), "pertaining to or resembling the planet Mars" (1620s). Related: Martially. Martial law, "military rule over civilians," first recorded 1530s. Martial arts (1909) as a collective name for the fighting sports of Japan and the surrounding region translates Japanese bujutsu.
"tract of water-soaked or partially flooded land; wet, swampy ground; piece of low ground, usually more or less wet but often nearly dry at certain seasons," Middle English mersh, from Old English mersc, merisc "marsh, swamp," from Proto-Germanic *marisko (source also of Old Frisian and Old Saxon marsk "marsh," Middle Dutch mersch, Dutch mars, German Marsch, Danish marsk), probably from Proto-Germanic *mari- "sea" (from PIE root *mori- "body of water").
The vowel shift from -e- to -a- began in 15c. and is usual for -er- followed by a consonant: Compare darling (Middle English dereling, Old English deorling), far (Middle English fer, Old English feorr), mar (Middle English merren), hart (Middle English hert, Old English heorot). Marsh gas "methane generated by decaying matter in marshes" is attested by 1819.
mid-13c., "high officer of the royal court," charged with regulating ceremonies and maintaining order (early 13c. as a surname), from Old French mareschal "commanding officer of an army; officer in charge of a household" (Modern French maréchal), originally "stable officer, horse tender, groom" (Frankish Latin mariscaluis) from Frankish *marhskalk or a similar Germanic word, literally "horse-servant" (compare Old High German marahscalc "groom," Middle Dutch maerschalc).
This is from a Proto-Germanic compound of *markhaz "horse" (see mare (n.1)) + *skalkaz "servant" (source of Old English scealc "servant, retainer, member of a crew," Dutch schalk "rogue, wag," Gothic skalks "servant"). It corresponds to Old English horsþegn.
From early 14c. as "military commander, general in the army." In the U.S., a civil officer appointed by the president (with advice and consent of the Senate) in each judicial district as the executive officer of the Supreme Court and the federal courts in his district. For sense development and the tendency of officers of the stable to become chief officers of royal households, compare constable. Also from Germanic are Italian scalco "steward," Spanish mariscal "marshal."
mid-15c., marshalen, "to tend (horses)," also "to arrange, place in order;" "arrange (soldiers) for fighting," from marshal (n.). Figurative use is by 1690s. Related: Marshaled; marshaling.