-plex

Borrowed from Latin -plex (“-fold”).

• IPA^(key): /-plɛks/

• Audio (US):

  (file)

-plex

1. Comprising a number of parts, as in duplex.
2. (mathematics) ten to the power of the number, as in googolplex.

• -fold

Disputed.

• Possibly from Proto-Italic *-pleks, from Proto-Indo-European *pleḱ- (“to plait, to weave”), making it equivalent to plicō (“to fold”) +‎ -s.
• Possibly from Proto-Italic *-plaks, with regular reduction of Proto-Italic *-a- to Latin -e- in a non-initial closed syllable.^[1]
• In either case, it may ultimately derive from an extension of Proto-Indo-European *pel- (“to fold”). Compare -plus.

Potential cognates include Umbrian -𐌐𐌋𐌀𐌊 (-plak), found in 𐌕𐌖𐌐𐌋𐌀𐌊 (tuplak), and Ancient Greek -πλαξ (-plax), found in δίπλαξ (díplax) and τρίπλαξ (tríplax).^[2][3]

• De Vaan 2008 derives Latin -plex from Proto-Italic *-pleks, from the e-grade of the root *pleḱ-, and Greek -πλαξ (-plax) from Proto-Indo-European *-pl̥ḱ-, the zero-grade ablaut variant of the same root. De Vaan considers the meaning and etymology of the Umbrian form to be unclear.^[2] At the same time, De Vaan reconstructs simplex as coming from Proto-Italic *sm̥-plak-s.^[4]
• Others accept the Umbrian form as a cognate, which suggests Proto-Italic *-plaks: this complicates the etymology from *pleḱ- (“to plait, to weave”). Flemestad and Olsen 2017 treat all three of duplex, 𐌕𐌖𐌐𐌋𐌀𐌊 (tuplak), and δίπλαξ (díplax) as cognates, and prefer to derive them from the root *pel- (“fold”) combined with a suffix *-ak-.^[5]
• Some argue that Greek -πλαξ (-plax) is not from *pleḱ- (“to plait, to weave”), but from an unrelated root found in πλάξ (pláx, “surface”), which van Beek 2022 identifies as coming from *plek‑ (“to strip, flay”).^[6]
• Coleman 1992 suggests duplex and 𐌕𐌖𐌐𐌋𐌀𐌊 (tuplak) might be derived from Proto-Indo-European *pleh₂- (“flat”), the root of plānus, which he considers to be an extension of *pel-.^[7]

• (Classical Latin) IPA^(key): [pɫɛks]
• (modern Italianate Ecclesiastical) IPA^(key): [pleks]

-plex (genitive -plicis); third-declension one-termination suffix

1. Creates adjectives specifying the number of times, -fold

   *sem- (“one”) → simplex (“onefold, single, simple”)

   tri- (“three”) → triplex (“threefold”)

   quadri- (“four”) → quadruplex (“fourfold”)

   centum (“hundred”) → centiplex (“hundredfold”)

   multus (“many”) → multiplex (“manifold”)

Third-declension one-termination adjective.

• → English: -plex