a closed plane curve resulting from the intersection of a circular cone and a plane cutting completely through it; "the sums of the distances from the foci to any point on an ellipse is constant"
a trap for birds or small mammals; often has a slip noose
strings stretched across the lower head of a snare drum; they make a rattling sound when the drum is hit
a surgical instrument consisting of wire hoop that can be drawn tight around the base of polyps or small tumors to sever them; used especially in body cavities