Conterminable is a word that is rarely used in everyday language, which makes it difficult to find synonyms that convey the same meaning. However, some possible synonyms for conterminable could be limitless, inexhaustible, interminable, or never-ending. These words suggest something that has no end or limit, which could be used in the context of time, space, or distance. Other synonyms that might be applicable include boundless, perpetual, everlasting, and unending. While these words are not exact replacements for conterminable, they do capture the sense of unending or infinite, which is what conterminable means.