IPA: /ˈʃeɪmˌfeɪsɪdli/
KK: /ˈʃeɪmˌfeɪsɪdli/
In a way that shows embarrassment or guilt.
He apologized shamefacedly after realizing his mistake.
Shamefacedly → It is formed from "shame" (from Old English *sceamu*, meaning a painful feeling of humiliation or distress) and "faced" (from Old French *face*, meaning the front part of the head). The suffix "-ly" (meaning in a manner) indicates the manner of being, thus "shamefacedly" means in a manner that shows shame on one's face.
Think of feeling 'shame' (the painful feeling) and showing it on your 'face' — that's why acting 'shamefacedly' means to show your shame on your face.