Q From William Wall: Why is it that egregious means very foolish or blatant, whereas the formal salutation egregio in Italian is clearly intended as a compliment, as in ‘Egregio Signore’?
A It’s the result of an odd shift of meaning in sixteenth-century England. Originally, something or someone egregious was remarkable in a good sense — distinguished, eminent or renowned — much as is implied in the Italian form of address. Both languages have taken it from Latin egregius, which actually means “standing out from the herd” (greg is an inflected form of grex, a herd or flock).
But then — only 50 years after it first appeared in English — the word started to be used jokingly in reference to somebody who stood out from the crowd in a bad way, notoriously or outrageously. This quickly became established and both senses ran in parallel for some 200 years (which must have been awkward for readers). Christopher Marlowe employed it in the older sense in his Tamburlaine in 1590: “Egregious viceroys of these eastern parts”, while in 1611 Shakespeare has Posthumus describe himself in Cymbeline in the newer condemnatory sense: “Egregious murderer”.
By the nineteenth century our modern strongly negative meaning of something outstandingly bad or shocking had triumphed.