Definition of "chirrup" [chir•rup]

• To utter a series of chirps. (verb-intransitive)
• To make clucking or clicking sounds with the lips, as in urging on a horse. (verb-intransitive)
• To sound with chirps. (verb-transitive)
• To make clucking sounds to. (verb-transitive)
• A series of chirps. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Esther works on maintaining her attention only in the present; there is always the now—an endlessly adjusting smell of the wind, the shining of the stars, the deep five-call chirrup chirrup of the cicadas in the park."
• "Again, it should be known that the conventional "chirrup" (7) to quiet and "cluck" to rouse a horse are a sort of precept of the training school; and supposing any one from the beginning chose to associate soft soothing actions with the "cluck" sound, and harsh rousing actions with the "chirrup," the horse could be taught to rouse himself at the"
• "At night other sounds are heard, less agreeable to the ear: the shrill "chirrup" of cicadas and tree-toads ringing so incessantly, that only when they cease do you become conscious of their existence; the dull "gluck-gluck" of the great bullfrog; the sharp cries of the heron and _qua-bird_; and the sepulchral screech of the great horned owl."