Conterminous is an adjective that means sharing a common boundary.

The Latin word terminus (TEAR me noos) means ‘border.’ When combined with the Latin prefix C-O-N, we get a word that means ‘sharing a border.’ Two things are regarded as conterminous if they share a common boundary.

I’ve been to all forty-eight states that are conterminous with each other in the US. Someday, I hope to visit Alaska and Hawaii outside of the that boundary.