What is coy?

It seems like you might be referring to "COY," which can stand for different things, or perhaps you meant "coy," an adjective describing a person or behavior. Below are explanations for each possible interpretation:

Coy (Adjective):

Definition: The term "coy" often describes someone who is pretending to be shy or modest in a playful or provocative manner. It can also refer to being evasive or reluctant to provide information.
Usage: Often used to describe a person or their behavior, for example, "She gave a coy smile."
Context: Can be romantic or social, often implying a level of flirtation or playful reluctance.

COY (Possible Acronyms):

While you didn't specify an acronym, COY could refer to any number of things depending on context. Here are a few possibilities:

COY - Company of the Year: An award or recognition given by various organizations to businesses or entities that excel in their industry.
COY - Conference of Youth: An annual event where youth from around the world gather to discuss environmental issues, especially related to climate change. It typically takes place prior to the United Nations Climate Change Conference (COP).
COY - Cutoff Year: In various contexts, "cutoff year" could refer to the year after which certain rules, policies, or considerations apply in a different way.

If you had a specific context in mind, please provide more details for a more precise response.