We only call them "tonics" in MA and southern NH. Especially if they are the ones bottled at the Polar plant in Worcester! They call them "sodas" or "soda pops" elsewhere! Just a small translation for non-MA folks who are reading. :-)
FReegards!
LOL...I see the polar bear off of 290 as you pass though Worcester...
The usage of the word is intended in the following definitions:
1. An agent, such as a medication, that restores or increases body tone.
2. An invigorating, refreshing, or restorative agent or influence.