daft
adjective /dɑːft/
  /dæft/
 (comparative dafter, superlative daftest)
 (informal)Idioms - silly, often in a way that is funny- Don't be so daft!
- She's not as daft as she looks.
- What a daft thing to say!
- The decision is just plain daft.
 Word OriginOld English gedæfte ‘mild, meek’, of Germanic origin; related to Gothic gabadan ‘become or be fitting’.
Idioms 
daft as a brush 
- (British English, informal) very silly