I was appalled by his shameless attitude.
You must not trust a person who tells brazen lies.
He's a shameless person who lies without any hesitation.
He shamelessly claimed someone else's achievement as his own.
破廉恥 emphasizes scandalous, morally outrageous shamelessness (often in legal or public-scandal contexts), whereas 無恥 is a broader, plainer term for lacking shame.
厚顔無恥 is a four-character compound meaning 'brazen-faced and shameless', more emphatic and literary than 無恥 used alone.
無知 (むち) means 'ignorant, lacking knowledge', while 無恥 (むち) means 'shameless, lacking a sense of shame'—they share a reading but differ completely in meaning.
shameless; brazen; unscrupulous
A Sino-Japanese compound of 無 (mu, 'without') and 恥 (chi, 'shame'). The exact historical derivation is uncertain, but the meaning follows directly from the kanji components.