pent, quin

five

Spelled pent, quin · pente 'five' (Greek); cf. Latin quinque 'five'

Greek pente and Latin quinque mean five: a pentagon has five angles, a quintet five performers, and a quinquennial spans five years.

Words built from it

pentagon — a five-sided figure
pent (five) + gon (angle)
pentagram — a five-pointed star
pent (five) + gram (something written or drawn)
quintet — a group of five, especially musicians
quin (five) + -et (small group)
pentathlon — an athletic contest made up of five events
pent (five) + athlon (contest)
quintuple — five times as much or as many
quin (five) + -uple (fold, times)
quintessential — representing the most perfect or typical example
Latin quinta (fifth) + essentia (essence) → quintessence → quintessential
quintessence — the purest, most perfect embodiment of something
quin (five) + essence (being, substance)

repent — from Old French repentir, from re- + Latin paenitere 'to regret'; unrelated to Greek pente / Latin quinque 'five'.
penthouse — an alteration of Middle English pentis, from Old French apentis, from Latin appendere 'to hang onto'; unrelated to 'five'.