Definitions

1. adjective

unconventional, quirky, or unconventional in a charming or amusing way

“The whacky artist’s use of colors made their paintings stand out.”

2. adverb

in a whacky or unconventional way

“She danced whacky to the beat of the music.”

3. noun

a person or thing that is unconventional or quirky

“The whacky character in the movie stole the show.”