Entry 2 senses Webster, 1913 Terminator /tẽrm'-ən-ātˌ-ẽr/ · Ter·mi·na·tor · IPA /ˈtɝ.mɪˌneɪ.tɚ/ 01 n. One who, or that which, terminates. 1. One who, or that which, terminates. 2. The dividing line between the illuminated and the unilluminated part of the moon.(Astron.)