Definition of cotton on
- It took a while, but they are finally starting to cotton on.
- She cottoned on to the fact that I like her.
: a soft usually white fibrous substance composed of the hairs surrounding the seeds of various erect freely branching tropical plants (genus Gossypium) of the mallow family
: a plant producing cotton
: a crop of cotton
: to take a liking
: to come to understand
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