a cookie is a

In the United States and Canada a cookie is a small, flat, baked treat, usually containing fat, flour, eggs and sugar. In Scotland the term cookie is sometimes used to describe a plain bun. In most English-speaking countries outside North America, including the United Kingdom, the most common word for a small, flat, baked treat, usually containing fat, flour, eggs and sugar is biscuit and the term cookie is often used to describe drop cookies exclusively.
Cookies are most commonly baked until crisp or just long enough that they remain soft, but some kinds of cookies are not baked at all. Cookies are made in a wide variety of styles, using an array of ingredients including sugars, spices, chocolate, butter, peanut butter, nuts or dried fruits. The softness of the cookie may depend on how long it is baked. Cookies appear to have their origins in 7th century Persia, shortly after the use of sugar became relatively common in the region and then spread to Europe.
Cookies came to America in the early English settlement in 17th century by the name "koekje" it arrived with the Dutch.
This became Anglicized to "cookie" or cooky. Among the popular early American cookies were the macaroon, gingerbread cookies, and of course jumbles of various types.