"perplex or embarrass by suddenly exciting the conscience, discomfit, make ashamed," late 14c., abaishen, earlier "lose one's composure, be upset" (early 14c.), from Old French esbaiss-, present stem of esbaer "lose one's composure, be startled, be stunned."

Originally, to put to confusion from any strong emotion, whether of fear, of wonder, shame, or admiration, but restricted in modern times to effect of shame. [Hensleigh Wedgwood, "A Dictionary of English Etymology," 1859]

The first element is es "out" (from Latin ex; see ex-). The second may be ba(y)er "to be open, gape" (if the notion is "gaping with astonishment"), possibly ultimately imitative of opening the lips. Middle English Compendium also compares Old French abaissier "bow, diminish, lower oneself" (source of abase). Related: Abashed; abashing. Bashful is a 16c. derivative.

c. 1300, "fear, terror, state of alarm produced by a sudden disturbance," from Old French affrai, effrei, esfrei "disturbance, fright," from esfreer (v.) "to worry, concern, trouble, disturb," from Vulgar Latin *exfridare, a hybrid word meaning literally "to take out of peace."

The first element is from Latin ex "out of" (see ex-). The second is Frankish *frithu "peace," from Proto-Germanic *frithuz "peace, consideration, forbearance" (source also of Old Saxon frithu, Old English friðu, Old High German fridu "peace, truce," German Friede "peace"), from a suffixed form of PIE root *pri- "to be friendly, to love."

The meaning "breach of the peace, riotous fight in public" is from late 15c., via the notion of "disturbance causing terror." The French verb also entered Middle English, as afrey "to terrify, frighten" (early 14c.), but it survives almost exclusively in its past participle, afraid (q.v.).