-plexsuff. Divided into a specified number of parts: fourplex.[From Latin -plex, -fold (as in duplex, twofold); see plek- in Indo-European roots.]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.-plex a combining form meaning ?having parts or units? of the number specified by the initial element, occurring orig. in loanwords from Latin (duplex); recent English coinages ending in -plex are probably in part new formations with this suffix and in part based on the noun complex: eightplex; Cineplex; Metroplex. [