From Longman Dictionary of Contemporary Englishbrainlessbrain‧less /ˈbreɪnləs/ adjective STUPID/NOT SENSIBLEcompletely stupid What a brainless thing to do! —brainlessly adverb
Examples from the Corpus
brainless• He had the body of an athlete, every sinew honed down to perfection, but he wasn't brainless.• Married doesn't mean redundant and most definitely doesn't mean brainless.• He was the ideal caricature used by brainless, anti-semitic writers of fiction who were conceived in sewers.• You brainless idiot!• My sister's latest boyfriend is pretty brainless; it's impossible to have a conversation with him.• 'You brainless scum!' he shouted after the departing boys. 