c. 1200, perhaps mid-12c., "well-born man, man of good family or birth," also extended to Roman patricians and ancient Greek aristocrats, from gentle + man (n.); the compound probably is modeled on Old French gentilhomme (the English gentleman itself was borrowed into French in 18c.).
Given specific uses in late Middle English (small gentleman, gentleman-of-arms, gentleman-usher, etc.), hence in England the word often meant any man above the social rank of a yeoman, including the nobility, but it was sometimes restricted to those who bear a coat of arms but not a title; in U.S., "man of property, not engaged in business or a profession" (1789). The English word from the beginning also had a special sense "nobleman whose behavior conforms to the ideals of chivalry and Christianity," and gentleman came to be used loosely for any man of good breeding, courtesy, kindness, honor, strict regard for the feelings of others, etc.
[The Gentleman] is always truthful and sincere ; will not agree for the sake of complaisance or out of weakness ; will not pass over that of which he disapproves. He has a clear soul, and a fearless, straightforward tongue. On the other hand, he is not blunt and rude. His truth is courteous ; his courtesy, truthful ; never a humbug, yet, where he truthfully can, he prefers to say pleasant things. [The Rev. John R. Vernon, "The Grand Old Name of Gentleman," in Contemporary Review, vol. XI, May-August 1869]
Eventually, in polite use, it came to mean a man in general, regardless of social standing. Related: Gentlemen. Gentleman's agreement is first attested 1929. Gentleman farmer recorded from 1749, "A man of means who farms on a large scale, employs hands, and does little or none of the work himself" [Craigie, "Dictionary of American English"].
late Old English prud, prute "excellent, splendid; arrogant, haughty, having or cherishing a high opinion of one's own merits; guilty of the sin of Pride," from Old French prud, oblique case of adjective prouz "brave, valiant" (11c., Modern French preux; compare prud'homme "brave man"), from Late Latin prode "advantageous, profitable" (source also of Italian prode "valiant"), a back-formation from Latin prodesse "be useful."
This is a compound of pro- "before, for, instead of" (from PIE root *per- (1) "forward," hence "in front of, before, first, chief") + esse "to be" (from PIE root *es- "to be"). Also see pride (n.), prowess. "The -d- in prodesse is probably due to the influence of forms like red-eo-, 'I go back,' red-imo- 'I buy back,' etc." [OED]. The Old English form with -te probably is from or influenced by pride (Old English pryto).
Meaning "elated by some act, fact, or thing" is from mid-13c. The sense of "of fearless or untamable spirit" is by c. 1400; that of "ostentatious, grand, giving reason for pride" is by mid-14c. To do (someone) proud is attested by 1819. The surname Proudfoot is attested from c. 1200 (Prudfot). A Middle English term for "drunk and belligerent" was pitcher-proud (early 15c.).
The sense of "having a high opinion of oneself," not found in Old French, might reflect the Anglo-Saxons' opinion of the Norman knights who called themselves "proud." Old Norse pruðr, either from the same French source or borrowed from Old English, had only the sense "brave, gallant, magnificent, stately" (compare Icelandic pruður, Middle Swedish prudh, Middle Danish prud).
Likewise a group of "pride" words in the Romance languages — such as French orgueil, Italian orgoglio, Spanish orgullo — are borrowings from Germanic, where they had positive senses (Old High German urgol "distinguished").
Most Indo-European languages use the same word for "proud" in its good and bad senses, but in many the bad sense seems to be the earlier one. The usual way to form the word is by some compound of terms for "over" or "high" and words for "heart," "mood," "thought," or "appearance;" such as Greek hyperephanos, literally "over-appearing;" Gothic hauhþuhts, literally "high-conscience." Old English had ofermodig "over-moody" ("mood" in Anglo-Saxon was a much more potent word than presently) and heahheort "high-heart."
Words for "proud" in other Indo-European languages sometimes reflect a physical sense of being swollen or puffed up; such as Welsh balch, probably from a root meaning "to swell," and Modern Greek kamari, from ancient Greek kamarou "furnish with a vault or arched cover," with a sense evolution via "make an arch," to "puff out the chest," to "be puffed up" (compare English slang chesty).