锥 is a bound morpheme — it cannot stand alone as a word. You’ll find it inside compounds for different but related concepts: 锥子 (awl), 圆锥 (cone in math), 锥体 (cone shape), and 改锥 (screwdriver). It can also appear as a component in a few verbs like 钻孔 (drill a hole), where 钻 is the verb and 孔 is the object.