·noun The key tone, or first tone of any scale.
II. Tonic ·noun A tonic element or letter; a vowel or a diphthong.
III. Tonic ·noun A medicine that increases the strength, and gives vigor of action to the system.
IV. Tonic ·add. ·adj Characterized by continuous muscular contraction; as, tonic convulsions.
V. Tonic ·adj Of or pertaining to tension; increasing tension; hence, increasing strength; as, tonic power.
VI. Tonic ·adj Increasing strength, or the tone of the animal system; obviating the effects of debility, and restoring healthy functions.
VII. Tonic ·adj 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.".