[a. late L. terminātor, agent-n. f. termināre to TERMINATE.]

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  1.  One who or that which terminates.

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1846.  Worcester, Terminator, he or that which terminates or bounds.

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1890.  Illustr. Lond. News, 27 Dec., 810/2. The terminator of delights,… the desolator of abodes.

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  2.  Astron. The line of separation between the illuminated and unilluminated parts of the disk of the moon or a planet.

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1770.  Horsley, in Phil. Trans., LX. 435, note. A great circle passing through the poles of the terminator.

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1868.  Lockyer, Elem. Astron., III. xvi. (1879), 92. The terminator—the name given to the boundary between the lit-up and shaded portions [of the Moon].

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1876.  G. F. Chambers, Astron., 69. Schröter found the terminator [of Venus] slightly concave.

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