Acicula and Cusp

Acicula noun - A needlelike part or structure of a plant or animal or crystal; as a spine or bristle or crystal.

Cusp and acicula are semantically related in point topic. In some cases you can use "Cusp" instead a noun "Acicula", when it comes to topics like sharp.

Cusp noun - An interval of time just before the onset of something.

Acicula and cusp are semantically related in sharp topic. You can use "Acicula" instead a noun "Cusp".