web

in anatomy
synonym: webbing
https://doi.org/10.1351/goldbook.11378

Tissue or membrane present between adjacent structures where it is not usually found, e.g., between fingers or toes, or between the neck and shoulder, representing a congenital abnormality.

Source:
PAC, 2016, 88, 713. (Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)) on page 821 [Terms] [Paper]