tonic

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An agent, such as a medication, that is supposed to restore or improve health or well-being.
• noun A liquid preparation for the scalp or hair.
• noun An invigorating, refreshing, or restorative agent or influence.
• noun Music The first note of a diatonic scale; the keynote.
• noun Linguistics A tonic accent.
• adjective Restorative or stimulating to health or well-being.
• adjective Physiology Of, relating to, or producing tone or tonicity in muscles or tissue.
• adjective Medicine Characterized by continuous tension or contraction of muscles.
• adjective Music Of or based on the keynote.
• adjective Stressed, as a syllable; accented.

from The Century Dictionary.

• Characterized by distinctive tones. Same as toned, 2. See tone, 15.
• Of or relating to tones or musical sounds.
• Specifically, in music, of or pertaining to, or founded on, the key-note or tonic.
• Of or pertaining to tension; increasing tension.
• In medicine, increasing the strength or tone of the animal system; obviating the effects of weakness or debility, and restoring healthy functions; hence, bracing or invigorating to the mental or the moral nature.
• noun In medicine, any remedy which improves the tone or vigor of the fibers of the stomach and bowels, or of the muscular fibers generally.
• noun In music, same as key-note. See also key, 7 .

from the GNU version of the Collaborative International Dictionary of English.

• adjective 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.”
• adjective Of or pertaining to tension; increasing tension; hence, increasing strength.
• adjective (Med.) Increasing strength, or the tone of the animal system; obviating the effects of debility, and restoring healthy functions.
• adjective (Med.) Characterized by continuous muscular contraction.
• adjective (Med.) See the Note under Spasm.
• noun (Phon.) A tonic element or letter; a vowel or a diphthong.
• noun (Mus.) The key tone, or first tone of any scale.
• noun (Med.) A medicine that increases the strength, and gives vigor of action to the system.
• noun (Mus.) the name of the most popular among letter systems of notation (at least in England), based on key relationship, and hence called “tonic.” Instead of the five lines, clefs, signature, etc., of the usual notation, it employs letters and the syllables do, re, mi, etc., variously modified, with other simple signs of duration, of upper or lower octave, etc. See Sol-fa.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective music Pertaining to the keynote of a composition.
• adjective Pertaining to the accent or stress in a word or in speech.
• noun music The first note of a scale.
• noun music The triad built on the tonic note.
• adjective physics, pathology Pertaining to tension, especially of muscles.
• adjective Restorative, curative or invigorating.
• noun A drink intended to restore or invigorate.
• noun Tonic water.
• noun US, Northeastern US Any of various carbonated, non-alcoholic beverages; soda pop.
• noun figuratively Something that revitalises or reinvigorates.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a sweet drink containing carbonated water and flavoring
• noun lime- or lemon-flavored carbonated water containing quinine
• adjective imparting vitality and energy
• adjective employing variations in pitch to distinguish meanings of otherwise similar words
• adjective used of syllables
• adjective relating to or being the keynote of a major or minor scale
• noun a medicine that strengthens and invigorates
• adjective of or relating to or producing normal tone or tonus in muscles or tissue
• noun (music) the first note of a diatonic scale