a combining form meaning "having parts or units" of the number specified by the initial element, occurring originally in loanwords from Latin ( duplex; quadruplex ); recent English coinages ending in -plex, esp. denoting structures with a given number of dwelling units, are probably in part new formations with this suffix and in part based on the noun complex: fourplex; eightplex; Cineplex; Metroplex.
[ -plex, -plic- (akin to plicare to fold, bend, plectere to plait, braid; see -FOLD) + -s nom. sing. ending ]