silly
1. Lacking seriousness; groundless lightheartedness.
2. Harmless; innocent; inoffensive.
3. Weak in intellect; destitute of ordinary strength of mind; foolish.
airheaded · cockamamie · cockamamy · confused · dizzy · empty-headed · featherbrained · foolish · frivolous · giddy · goofy · light-headed · lightheaded · pathetic · punch-drunk · ridiculous · sappy · slaphappy · undignified · wacky · whacky · zany
Sillitoe · sillograph · sillometer · sills · silly · silly as a wheel · silly ass · silly asses