tonic (adj) – invigorating or restorative; of or pertaining to tension
BREAKDOWN: TON- (tone) + -IC (pertaining to)
— a tonic is a drink or medicine intended to invigorate, stimulate, or restore
This word is built on the root TON-, which means tension, tone, sound, or thunder.
Common TON- words include astonish, detonate, monotonous, thunder, tone, and tune.
More esoteric TON- words include atonic and ecotone.