Definition of "opercular" [o•per•cu•lar]

• Of or pertaining to the operculum. (adjective)
• The principal opercular bone or operculum of fishes. (noun)

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• "Tiktaalik is transitional in the evolutionary shift from the pharyngeal and opercular pumps employed by fish to the buccal and costal pumping mechanisms of tetrapods."
• "Again, with reference to the homology of the ossicles of the ear with the opercular bones in fish, "employing other resources equally hidden and rudimentary, Nature makes profitable use of the four tiny ossicles lodged in the auditory passage, and, raising them in fish to the greatest possible dimensions, forms from them these broad opercula ...." (p. 85)."
• "Or you may take it the other way about, and start from the organisation of fishes; opercular bones are of no use to air-breathing animals, so they dwindle away, and are pressed into the service of the ear, although they are of little use in hearing (p. 46)."