before vowels quinqu-, word-forming element from classical Latin meaning "five, consisting of or having five," from Latin quinque "five" (by assimilation from PIE root *penkwe- "five").
Entries linking to quinque-
*penkwe-
Proto-Indo-European root meaning "five."
It forms all or part of: cinquain; cinque; cinquecento; cinquefoil; fifteen; fifth; fifty; fin (n.) "five-dollar bill;" finger; fist; five; foist; keno; parcheesi; penta-; pentacle; pentad; Pentateuch; Pentecost; pentagon; pentagram; pentameter; pentathlon; Pentothal; Pompeii; Punjab; punch (n.2) "type of mixed drink;" quinary; quincunx; quinella; quinque-; quinquennial; quint; quintain; quintet; quintile; quintessence; quintillion; quintuple.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit panca, Greek pente, Latin quinque, Old Church Slavonic pęti, Lithuanian penki, Old Welsh pimp, Old English fif, Dutch vijf, Old High German funf.
fifteen adj., n.
"1 more than fourteen; the number which is one more than fourteen; a symbol representing this number;" Old English fiftyne, from fif "five" (from PIE root *penkwe- "five") + tyne (see -teen). For vowel shift, see met (v.). Cognate with Old Saxon fiftein, Old Frisian fiftine, Old Norse fimtan, Swedish femton, Dutch vijftien, German fünfzehn, Gothic fimftaihun "fifteen." French quinze, Italian quindici "fifteen" are from Latin quindecim (from quinque "five;" see quinque-; + -decim (see -teen). The number of players forming a side in rugby.