資料來源 : Webster's Revised Unabridged Dictionary (1913)

Tonic \Ton"ic\, a. [Cf. F. tonigue, Gr. ?. See {Tone}.]
   1. Of or relating to tones or sounds; specifically (Phon.),
      applied to, or distingshing, a speech sound made with tone
      unmixed and undimmed by obstruction, such sounds, namely,
      the vowels and diphthongs, being so called by Dr. James
      Rush (1833) `` from their forming the purest and most
      plastic material of intonation.''

   2. Of or pertaining to tension; increasing tension; hence,
      increasing strength; as, tonic power.

   3. (Med.) Increasing strength, or the tone of the animal
      system; obviating the effects of debility, and restoring
      healthy functions.

   {Tonic spasm}. (Med.) See the Note under {Spasm}.