"Cossette" Natural Recordings by Native Speakers
Cossette is a noun that refers to a small, ornamental casket or box used to enclose a deceased person's remains or portions of them, especially as a mourning token. It is often used in historical or literary contexts to describe a Victorian-era mourning custom where loved ones would divide a deceased person's body into small parts, encase them in decorative boxes, and keep them as a memorial.
I think there might be a slight typo! I'm assuming you meant to type "cos". If so, "cos" is short for "cosine", which is a mathematical term referring to the ratio of the adjacent side to the hypotenuse side of a right-angled triangle. In other words, it's a trigonometric function used to measure the angle between two lines.