er·u·dite (ry-dt, r-) KEY
Middle English erudit, from Latin rudtus, past participle of rudre, to instruct : -, ex-, ex- + rudis, rough, untaught ; see rude
One might like to be erudite but hesitate to be rude. This preference is supported by the etymological relationship between erudite and rude. Erudite comes from the Latin adjective rudtus, "well-instructed, learned," from the past participle of the verb rudre, "to educate, train." The verb is in turn formed from the prefix ex-, "out, out of," and the adjective rudis, "untaught, untrained," the source of our word rude. The English word erudite is first recorded in a work possibly written before 1425 with the senses "instructed, learned." Erudite meaning "learned" is supposed to have become rare except in sarcastic use during the latter part of the 19th century, but the word now seems to have been restored to favor.