adjective
1.
increasing or restoring physical or mental tone
the tonic effect of a vacation
Synonyms: astringent, restorative, roborant
Related Word: invigorating, refreshing, renewing, strengthening; bracing, sharp
Contrasted words: debilitating, enfeebling, weakening; enervating; exhausting, grueling, sapping
2.
Synonyms: invigorating , animating, bracing, exhilarating, exhilarative, quickening, stimulating, stimulative, vitalizing