the word "unmusical" is a modern english formation built upon the well-established adjective "musical." the core element, "music," traces its lineage to ancient greek mousikē, which encompassed all arts presided over by the muses, later narrowing specifically to the art of sound and melody as it passed through latin. the suffix "-al," of latin origin, is routinely attached to nouns to create adjectives denoting a quality or relation. finally, the old english prefix "un-," a prolific negator in the language, is prefixed to invert the meaning. thus, the literal construction "not relating to music" logically yields the modern senses of either being discordant in sound or lacking musical aptitude.

Structure: un (not) + music (melody, art of sound) + al (adjective suffix) un: a prefix of germanic origin (old english) meaning "not," used to form negatives. music: from latin musica and greek mousikē (tekhnē), meaning "(art) of the muses," referring to melody or the art of sound. al: a suffix from latin -alis, used to form adjectives meaning "of, relating to, or characterized by."