Merriam-Webster's Collegiate® Dictionary, 11th Edition
BLUSH
I. noun
Etymology: Middle English, probably from blusshen
Date: 14th century
outward appearance ; view , a reddening of the face especially from shame, modesty, or confusion, a red or rosy tint, a cosmetic applied to the face to give a usually pink color or to accent the cheekbones, blushful adjective
II. intransitive verb
Etymology: Middle English blusshen, from Old English blyscan to redden; akin to Old English blȳsa flame, Old High German bluhhen to burn brightly
Date: 15th century
to become red in the face especially from shame, modesty, or confusion, to feel shame or embarrassment, to have a rosy or fresh color ; bloom , blushingly adverb