n. [ Gr. &unr_;, for &unr_; &unr_; the same + &unr_; time: cf. F. tautochrone. ] (Math.) A curved line, such that a heavy body, descending along it by the action of gravity, will always arrive at the lowest point in the same time, wherever in the curve it may begin to fall; as, an inverted cycloid with its base horizontal is a tautochrone. [ 1913 Webster ]

a. (Math.) Occupying the same time; pertaining to, or having the properties of, a tautochrone. [ 1913 Webster ]

n. [ The pl. of taut, the American Indian name, translated by Roger Williams sheep's heads, and written by him tautaúog. ] (Zool.) An edible labroid fish (Haitula onitis, or Tautoga onitis) of the Atlantic coast of the United States. When adult it is nearly black, more or less irregularly barred, with greenish gray. Called also blackfish, oyster fish, salt-water chub, and moll. [ Written also tautaug. ] [ 1913 Webster ]

a. Tautological. [ 1913 Webster ]

a. [ Cf. F. tautologique. ] Involving tautology; having the same signification; as, tautological expression. -- Tau`to*log"ic*al*ly, adv. [1913 Webster]

Tautological echo, an echo that repeats the same sound or syllable many times. [1913 Webster]

n. One who uses tautological words or phrases. [ 1913 Webster ]

v. i. [ imp. & p. p. Tautologized p. pr. & vb. n. Tautologizing ] To repeat the same thing in different words. [ 1913 Webster ]

a. [ Gr. &unr_;; &unr_;, for &unr_; &unr_; the same + &unr_; to speak. ] Repeating the same thing in different words; tautological. [ R. ] Tooke. [ 1913 Webster ]

n. [ L. tautologia, Gr. &unr_;: cf. F. tautologie. ] (Rhet.) A repetition of the same meaning in different words; needless repetition of an idea in different words or phrases; a representation of anything as the cause, condition, or consequence of itself, as in the following lines: --

The dawn is overcast, the morning lowers,
And heavily in clouds brings on the day. Addison. [ 1913 Webster ]

Syn. -- Repetition. -- Tautology, Repetition. There may be frequent repetitions (as in legal instruments) which are warranted either by necessity or convenience; but tautology is always a fault, being a sameness of expression which adds nothing to the sense or the sound. [ 1913 Webster ]

a. (Chem.) Relating to, or characterized by, tautomerism. [ 1913 Webster ]

n. [ Gr. &unr_;; &unr_;, for &unr_; &unr_; the same + &unr_; part. ] (Chem.) The condition, quality, or relation of metameric substances, or their respective derivatives, which are more or less interchangeable, according as one form or the other is the more stable. It is a special case of metamerism; thus, the lactam and the lactim compounds exhibit tautomerism. [ 1913 Webster ]

{ } a. [ Gr. &unr_;; &unr_;, for &unr_; &unr_; the same + &unr_; being, essence. ] Having the same essence; being identically of the same nature. [ R. ] Cudworth. [ 1913 Webster ]

a. Pertaining to, or characterized by, tautophony; repeating the same sound. [ 1913 Webster ]

n. [ Gr. &unr_;; &unr_;, for &unr_; &unr_; the same + &unr_; voice. ] Repetition of the same sound. [ 1913 Webster ]

a. [ Gr. &unr_;; &unr_;, for &unr_; &unr_; the same + E. zonal. ] (Crystallog.) Belonging to the same zone; as, tautozonal planes. [ 1913 Webster ]