In Italian, the word for two states which share part of their border is confinante (its plural is confinanti). For example, I could use that word for Italy and France, Spain and Portugal, or France and Germany. I would not use it for Italy and Germany, since there are two other states between Italy and Germany.
Looking for a translation of that word, I find:
- Adjoining: adiacente, contiguo, confinante, limitrofo
- Conterminous: confinante
The first word seems too generic, as adiacente could be said also for a street; the other word seem more specific, but I am not sure it is a word currently used.
Which word should I use?