stupid or foolish
WordReference Random House Learner's Dictionary of American English © 2025
brain•less /ˈbreɪnlɪs/USA pronunciation
adj.
WordReference Random House Unabridged Dictionary of American English © 2025- lacking intelligence or good sense;
stupid;
foolish.
brain•less
(brān′lis),USA pronunciation adj.
brain′less•ly, adv.
brain′less•ness, n.
- mentally weak;
foolish;
witless;
stupid.
- late Middle English braynles. See brain, -less 1400–50
brain′less•ness, n.
Collins Concise English Dictionary © HarperCollins Publishers::
'brainless' also found in these entries (note: many are not synonyms or translations):