-plex
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, especially 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.
Origin of -plex
< Latin
-plex, -plic- (akin to
plicāre to fold, bend,
plectere to plait, braid; see
-fold) +
-s nominative singular ending