1. a person or entity that is legally or morally bound to fulfill an obligation; one who is obligated
Usage: formal, legal context
2. in biology, an organism that is obligated to live in a particular way or environment and cannot survive otherwise
Usage: scientific, biology

Examples

• The obligator in the contract must complete the work by the deadline.
• As the obligator, the company is responsible for meeting all terms of the agreement.
• An obligate anaerobe is an obligator that cannot survive in the presence of oxygen.
• The obligator and obligee have reciprocal duties under the law.
• In this legal dispute, the obligator failed to fulfill their contractual duties.