The exactly etymology is uncertain, but it is most often derived from Latin circinus (itself from Ancient Greek κίρκινος (kírkinos)), which however, should have normally yielded a *cercen or *cearcen in Romanian according to phonetic rules; some have sought to derive it from a cearcene, plural of the hypothetical *cearcen, by analogy with other words like gemene - geamăn, mesteceni - mesteacăn, cf. also leagăne - leagăn, etc. Alternatively, the word may have come instead from a Vulgar Latin *carcinus, from Ancient Greek καρκίνος (karkínos), which meant "crab" and "cancer", but also "a pair of compasses", which fits with one of the older senses of this word (but is also found in Latin circinus, from another Greek root). From here and through an early Romanian root *carcen, the form cearcăn could have been reached through a process of metathesis. It is also possible that the word is an internal derivation from cerc (“circle”) in Romanian. Compare French cerne.
cearcăn n (plural cearcăne)