from
The Collaborative International Dictionary of English v.0.48
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."
[1913 Webster]
2. Of or pertaining to tension; increasing tension; hence,
increasing strength; as, tonic power.
[1913 Webster]
3. (Med.) Increasing strength, or the tone of the animal
system; obviating the effects of debility, and restoring
healthy functions.
[1913 Webster]
4. (Med.) Characterized by continuous muscular contraction;
as, tonic convulsions.
[Webster 1913 Suppl.]
{Tonic spasm}. (Med.) See the Note under {Spasm}.
[1913 Webster]