'Proud' meant 'valiant' in French — English adopted it chiefly as 'arrogant.' One of language's moral reversals.
Feeling deep pleasure or satisfaction from one's own achievements, qualities, or possessions; having an excessively high opinion of oneself.
From late Old English 'prūd, prūt' (having a high opinion of oneself), from Old French 'prud, prod' (brave, valiant, gallant), from Late Latin 'prōde' (advantageous, profitable), from Latin 'prōdesse' (to be of value, to be useful), from 'prōd-' (variant of 'prō,' for, in favor of) + 'esse' (to be). The word originally meant 'valiant' and 'worthy' in French — a compliment — but English adopted it primarily in the negative sense of 'arrogant.' The positive sense re-emerged later. Key roots: prō (Latin: "for, in favor of, forward"), esse (Latin: "to be").
English 'proud' and 'prude' are the same word. French 'prudefemme' (a virtuous, worthy woman) was shortened to 'prude' — someone excessively proper. Meanwhile, the masculine form 'prudhomme' (a worthy man) survives in the French surname Prud'homme. Pride began as valor; prudishness began as virtue.