martian
n. countablen. a person or living being from the planet Mars. You mostly see these characters in science fiction books and movies.
n. a hypothetical inhabitant of the planet Mars. The term describes a being of extraterrestrial origin and is predominantly utilized in the context of speculative fiction or planetary exploration discourse.
The movie is about a Martian who visits Earth.
Early science fiction writers often depicted a Martian as a green-skinned being with advanced technology living among dusty ruins.
The scientific community spent decades searching for microbial life on the Red Planet, hoping to find even simple evidence of a prehistoric Martian organism.
From Latin Mārtius (“of or belonging to the planet Mars”), with the adjective-forming suffix -an tacked on — a tidy piece of classical bookkeeping that has survived, with assorted local spellings, from Middle English marcien through modern French martien and on to Portuguese marciano. The Romans gave their war-god a planet; the planet later gained an adjective, and the adjective eventually acquired inhabitants.
The French were first to capitalise the form (Martien) for the imaginary resident of the red planet, a nicety English quietly borrowed.
Capitalized as a proper noun in all contexts; also functions as an adjective when describing things related to Mars.