Old English scamu, sceomu "feeling of guilt or disgrace; confusion caused by shame; disgrace, dishonor, insult, loss of esteem or reputation; shameful circumstance, what brings disgrace; modesty; private parts," from Proto-Germanic *skamo (source also of Old Saxon skama, Old Norse skömm, Swedish skam, Old Frisian scome, Dutch schaamte, Old High German scama, German Scham). The best guess is that this is from PIE *skem-, from *kem- "to cover" (covering oneself being a common expression of shame).
Until modern times English had a productive duplicate form in shand. An Old Norse word for it was kinnroði, literally "cheek-redness," hence, "blush of shame." Greek distinguished shame in the bad sense of "disgrace, dishonor" (aiskhyne) from shame in the good sense of "modesty, bashfulness" (aidos). To put (someone or something) to shame is mid-13c. Shame culture attested by 1947.
"modest, bashful," 1550s, folk etymology alteration of shamefast, from Old English scamfæst "bashful," literally "restrained by shame," or else "firm in modesty," from shame (n.) + -fæst, adjectival suffix (see fast (adj.)). Related: Shamefacedly; shamefacedness.
shamefaced, -fast. It is true that the second is the original form, that -faced is due to a mistake, & that the notion attached to the word is necessarily affected in some slight degree by the change. But those who, in the flush of this discovery, would revert to -fast in ordinary use are rightly rewarded with the name of pedants .... [Fowler]
It was active in forming compounds, such as shendful (Old English scandful) "shameful," shendship "disgrace;" Old English scandhus "house of ill-fame," scandlic "shameful," scandlufiende "loving shamefully," scandword "obscene language").