Having no excuse; not admitting of excuse or apology.(adjective)
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Use "excuseless" in a sentence
"This excuseless /ju/ is perpetuated in Teach Yourself Ancient Greek 2002, Alan Henry and Gavin Betts - a couple of Australian academics, at Monash, which is my old university."
"It is but just to say that Democrats of the better sort totally disapproved of this public indecency and excuseless outrage."
"Great God! Forgive an injury so wanton, so excuseless!"