-plex

Borrowed from Latin -plex (“-fold”).

• IPA^(key): /-plɛks/

• Audio (US):

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-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.
• 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).

• 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. At the same time, De Vaan reconstructs simplex as coming from Proto-Italic *sm̥-plak-s.
• 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-.
• 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”).
• 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-.

• (Classical Latin) IPA^(key):
• (modern Italianate Ecclesiastical) IPA^(key):

-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