The term "in terminable" means never-ending, and its antonyms are words that represent limited or defined duration. These antonyms may include words such as finite, limited, restricted, bounded, circumscribed, or confined. Each of these words implies a sense of boundaries, limits or a specific range of action that comes to completion at some point. The opposite of never-ending is limited, restricted, and defined duration. These words represent the time frame of something that is sure to come to an end. Therefore, where "in terminable" suggests something that goes on indefinitely without end, its antonyms indicate something that is confined by specific limits or a fixed endpoint.