n. [ It., fr. opera work, composition, opposed to an improvisation, fr. L. opera pains, work, fr. opus, operis, work, labor: cf. F. opéra. See Operate. ] 1. A drama, either tragic or comic, of which music forms an essential part; a drama wholly or mostly sung, consisting of recitative, arias, choruses, duets, trios, etc., with orchestral accompaniment, preludes, and interludes, together with appropriate costumes, scenery, and action; a lyric drama. [ 1913 Webster ]

2. The score of a musical drama, either written or in print; a play set to music. [ 1913 Webster ]

3. The house where operas are exhibited. [ 1913 Webster ]

Opera bouffe [ F. opéra opera + bouffe comic, It. buffo ],
Opera buffa [ It. ], light, farcical, burlesque opera. --
Opera box, a partially inclosed portion of the auditorium of an opera house for the use of a small private party. --
Opera comique [ F. ], comic or humorous opera. --
Opera flannel, a light flannel, highly finished. Knight. --
Opera girl or
Opera girls (Bot.), an East Indian plant (Mantisia saltatoria) of the Ginger family, sometimes seen in hothouses. It has curious flowers which have some resemblance to a ballet dancer, whence the popular name. Called also dancing girls. --
Opera glass, a short telescope with concave eye lenses of low power, usually made double, that is, with a tube and set of glasses for each eye; a lorgnette; -- so called because adapted for use at the opera, theater, etc. --
Opera hat, a gentleman's folding hat. --
Opera house, specifically, a theater devoted to the performance of operas. --
Opera seria [ It. ], serious or tragic opera; grand opera. [ 1913 Webster ]

a. Practicable. [ Obs. ] [ 1913 Webster ]

n. [ L. opus, operis, pl. opera work + -meter. ] An instrument or machine for measuring work done, especially for ascertaining the number of rotations made by a machine or wheel in manufacturing cloth; a counter. Ure. [ 1913 Webster ]

{ } n. The act of operating or working; operation. [ R. ] [ 1913 Webster ]

n. [ From neuter of L. operandus, gerundive of operari. See Operate. ] (Math.) The symbol, quantity, or thing upon which a mathematical operation is performed; -- called also faciend. [ 1913 Webster ]

a. [ L. operans, p. pr. of operari. See Operate. ] Operative. [ R. ] Shak. -- n. An operative person or thing. [ R. ] Coleridge. [ 1913 Webster ]

n. (Psychol.) A process for causing animals to behave in a specific manner by rewarding or punishing the animal each time it performs a certain act; after a time, the animal comes to associate the reward or punishment with the act, and will increase or decrease the frequency of performing that act. [ PJC ]

v. t. 1. To produce, as an effect; to cause. [ 1913 Webster ]

The same cause would operate a diminution of the value of stock. A. Hamilton. [ 1913 Webster ]

2. To put into, or to continue in, operation or activity; to work; as, to operate a machine. [ 1913 Webster ]

v. i. [ imp. & p. p. Operated p. pr. & vb. n. Operating. ] [ L. operatus, p. p. of operari to work, fr. opus, operis, work, labor; akin to Skr. apas, and also to G. üben to exercise, OHG. uoben, Icel. æfa. Cf. Inure, Maneuver, Ure. ] 1. To perform a work or labor; to exert power or strength, physical or mechanical; to act. [ 1913 Webster ]

2. To produce an appropriate physical effect; to issue in the result designed by nature; especially (Med.), to take appropriate effect on the human system. [ 1913 Webster ]

3. To act or produce effect on the mind; to exert moral power or influence. [ 1913 Webster ]

The virtues of private persons operate but on a few. Atterbury. [ 1913 Webster ]

A plain, convincing reason operates on the mind both of a learned and ignorant hearer as long as they live. Swift. [ 1913 Webster ]

4. (Surg.) To perform some manual act upon a human body in a methodical manner, and usually with instruments, with a view to restore soundness or health, as in amputation, lithotomy, etc. [ 1913 Webster ]

5. To deal in stocks or any commodity with a view to speculative profits. [ Brokers' Cant ] [ 1913 Webster ]

{ } a. Of or pertaining to the opera or to operas; characteristic of, suitable for, or resembling, the opera; as, an operatic voice. [ 1913 Webster +PJC ]