aflush (adj.)youdaoicibaDictYouDict
"blushing," 1880, from a- (1) + flush (n.) "redness in the face."
blush (v.)youdaoicibaDictYouDict
mid-14c., bluschen, blischen, probably from Old English blyscan "blush, become red, glow" (glossing Latin rutilare), akin to blyse "torch," from Proto-Germanic *blisk- "to shine, burn," which also yielded words in Low German (Dutch blozen "to blush") and Scandinavian (Danish blusse "to blaze; to blush"); ultimately from PIE *bhel- (1) "to shine, flash, burn" (see bleach (v.)).

For vowel evolution, see bury. Earliest recorded senses were "to shine brightly; to look, stare." Sense of "turn red in the face" (with shame, modesty, etc.) is from c. 1400. Related: Blushed; blushing.
erubescentyoudaoicibaDictYouDict
"Reddening; blushing", Mid 18th century: from Latin erubescent- 'blushing', from the verb erubescere, from e- (variant of ex-) 'out' + rubescere 'redden' (from rubere 'be red').