paracellular

This term is used exclusively within biological and medical contexts, specifically in histology and physiology. It describes a specific route of transport where substances move through the gaps between cells, contrasting with transcellular transport, where substances must pass through the cell membranes and cytoplasm.

Because it is a technical descriptor for a biological pathway, it is almost always used as an adjective modifying nouns like transport, pathway, or diffusion. It carries a neutral, scientific tone and is not used in casual conversation or non-scientific writing.