Fissure and Foramen

Fissure noun - An irregular usually narrow break in a surface created by pressure.

Foramen and fissure are semantically related In some cases you can use "Foramen" instead a noun "Fissure".

Foramen noun - A natural opening or perforation through a bone or a membranous structure.

Fissure and foramen are semantically related in opening in a solid object topic. Sometimes you can use "Fissure" instead a noun "Foramen".