From BiblePortal Wikipedia

Webster's Dictionary [1]

(1): ( superl.) Violent; tumultuous; boisterous; inclement; harsh; severe; - said of the weather, of storms, and the like; as, the rude winter.

(2): ( superl.) Characterized by roughness; umpolished; raw; lacking delicacy or refinement; coarse.

(3): ( superl.) Not finished or complete; inelegant; lacking chasteness or elegance; not in good taste; unsatisfactory in mode of treatment; - said of literature, language, style, and the like.

(4): ( superl.) Barbarous; fierce; bloody; impetuous; - said of war, conflict, and the like; as, the rude shock of armies.

(5): ( superl.) Of untaught manners; unpolished; of low rank; uncivil; clownish; ignorant; raw; unskillful; - said of persons, or of conduct, skill, and the like.

(6): ( superl.) Unformed by taste or skill; not nicely finished; not smoothed or polished; - said especially of material things; as, rude workmanship.

King James Dictionary [2]

RUDE, a. L. rudis. The sense is probably rough, broken, and this word may be allied to raw and crude.

1. rough uneven rugged unformed by art as rude workmanship, that is, roughly finished rude and unpolished stones. 2. Rough of coarse manners unpolished uncivil clownish rustic as a rude countryman rude behavior rude treatment a rude attack.

Ruffian, let go that rude uncivil touch.

3. Violent tumultuous boisterous turbulent as rude winds the rude agitation of the sea. 4. violent fierce impetuous as the rude shock of armies. 5. Harsh inclement as the rude winter. 6. Ignorant untaught savage barbarous as the rude natives of America or of New Holland the rude ancestors of the Greeks. 7. Raw untaught ignorant not skilled or practiced as rude in speech rude in arms. 8. Artless inelegant not polished as a rude translation of Virgil.

Vine's Expository Dictionary of NT Words [3]

1: Ἰδιώτης (Strong'S #2399 — Noun Masculine — idiotes — id-ee-o'-tace )

for which see Ignorant , No. 4, is translated "rude" in  2—Corinthians 11:6 .

American Tract Society Bible Dictionary [4]

 2 Corinthians 11:6 , Artless and unpolished.

International Standard Bible Encyclopedia [5]

rōōd  : Not "impolite" in English Versions of the Bible (except perhaps   2 Maccabees 12:14 ), but "untrained," "ignorant"; compare the modern phrase, "a rude drawing." So  Sirach 8:4 ( ἀπαίδεντος , apaı́deutos ) and   2 Corinthians 11:6 ( ἰδιώτης , idiṓtēs , 'though I lack technical training in rhetoric'); compare the King James Version and the Revised Version margin Sirach 21:24.