How to Say "tonic" in Spanish
The Spanish word for “tonic” is “cordial” — C2 level.
English → SpanishC2
nounC2formal
restorative beverage

Examples
El médico le recetó un cordial para fortalecer su espíritu.
The doctor prescribed a cordial to strengthen his spirit.
Masculine Noun
When used as a noun meaning a drink or medicine, it is always masculine ('el cordial').
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