Eu-

Eu- (Greek εὖ-, the combining form of the adjective ευς "good") is a prefix meaning "good, well". From PIE "*hsu-", it is cognate to Sanskrit "su-", Avestan "hu-", with the same meaning.

In English, the prefix occurs mostly in words directly loaned from Greek, such as eulogy, euphemism, evangelist, eucharist, eucalyptus, eudemonic, euonymous, euphoria, eurhythmy, euthanasia, eutrophy, but it has some productivity, combining with Greek loanwords that did not take the prefix in attested Greek, e.g. in eucaryote, eugenic, euchlorine, Eutopia.

Note that the "Eu-" in "Europe" is unrelated.

The antonymous prefix is dys- (δυσ-), PIE "*dus-", Sanskrit "dur-". This prefix appears to be more productive for new coinages, thus "dysangelical" is a nonce word expressing the opposite of "evangelical", or "dyslogy" expressing the opposite of "eulogy", "dysgenic" expressing the opposite of "eugenic", etc. It also frequently figures in terms for illnesses and ailments, such as dysarthrosis, dyslexia, etc.

ee also

*Bahuvrihi
*Upasarga
*Privative alpha