From Longman Dictionary of Contemporary Englishsillysil‧ly1 /ˈsɪli/ ●●● S2 adjective (comparative sillier, superlative silliest) 1 STUPID/NOT SENSIBLEnot sensible, or showing bad judgment Stop asking silly questions. You made a lot of silly mistakes. I left my keys at home, which was a pretty silly thing to do. ‘Shall we go for a walk?’ ‘Don’t be silly, it’s dark.’► see thesaurus at stupid2 STUPID/NOT SENSIBLEstupid in a childish or embarrassing way I feel so silly in this outfit. a silly hat I hate their parties – we always end up playing silly games.3 spokenJOKING/NOT SERIOUSSENSIBLE# not serious or practical They served us coffee in these silly little cups.4 → bore somebody silly5 → drink/laugh/scare etc yourself silly —silliness noun [uncountable]
Examples from the Corpus
silly• And, though I believe she is at heart a sensible girl, she might be driven to do something silly.• Summoning the presence not to say something catty, I said something silly.• You know the sort of thing ... Good, kind people, but extraordinarily silly.• Don't pay any attention to her - she's just being silly.• I have a question which might sound a bit silly.• Now don't be silly, get up off the floor.• One such came lolloping up to Meredith, a silly grin on its face.• Rehearsals over, a certain degree of moodiness or silly humor would overtake him.• You're just a silly little boy.• Life was too short to worry about every silly little detail.• We saw all these city people with their silly little sandals on.• You've made a lot of silly mistakes in this essay.• That was silly of me -- I just locked the trunk and the keys are inside.• I thought it was a damn silly place to park if some one wanted to take a leak in the bushes.• Do you mind if I ask a silly question?• I had locked myself out, which was a silly thing to do.• It's silly to build another room onto the house now.• I think you're silly to worry so much about your hair.a ... silly thing to do• Landing down wind is a silly thing to do.sillysilly2 noun spoken STUPID/NOT SENSIBLEused to tell someone that you think they are not behaving sensibly No, silly, I didn’t mean that.Examples from the Corpus
silly• No, silly, put it over there!Origin silly1 Old English sælig “happy” 