A silly person.
"The silly person laughed at his own mistake during the meeting."
lacking seriousness; given to frivolity
"a dizzy blonde"
"light-headed teenagers"
"silly giggles"
inspiring scornful pity
"how silly an ardent and unsuccessful wooer can be especially if he is getting on in years"
dazed from or as if from repeated blows
"knocked silly by the impact"
"slaphappy with exhaustion"
"punch-drunk with love"
Laughable or amusing through foolishness or a foolish appearance.
"The clown's oversized nose made his entrance look silly and hilarious to the audience."
In plain English: Silly means acting foolishly or making jokes that are not serious.
"The silly dog chased its own tail until it fell over laughing."
Usage: Use "silly" to describe something laughably foolish, such as a prank that looks stupid but is meant to be funny. Avoid confusing it with serious errors; the word implies lightheartedness rather than genuine incompetence or danger.
Sillily: in a silly manner.
"The toddler sang a silly song while dancing around the living room."
"They silly danced all night at the party."
The word silly comes from Old English, originally meaning "lucky" or "fortunate." Over time, its meaning shifted to describe someone as innocent, naive, and finally foolish.