Meaning

noun communicates two or more signals over a common channel

noun a movie theater than has several different auditoriums in the same building

adjective many and varied; having many features or forms

originEtymology tree Proto-Indo-European *mel-der. Proto-Indo-European *ml̥tós? Proto-Italic *moltos Latin multi- Proto-Indo-European *pel-der.? Latin -plex Latin multiplexlbor. English multiplex Learned borrowing from Latin multiplex, from multi- + -plex.

Etymology from Wiktionary, CC BY-SA 3.0