General:
* Drink
* Potion
* Liquid
* Quaff
* Concoction
Specific:
* For alcoholic drinks: booze, liquor, spirits, intoxicant
* For hot drinks: infusion, brew, concoction
* For cold drinks: refreshment, cooler, thirst-quencher
* For non-alcoholic drinks: soda, juice, water, tea, coffee
Formal:
* Elixir
* Potable
* Imbibition
* Sustenance
* Refreshment
Informal:
* Sip
* Gulp
* Swig
* Something to drink
The best synonym will depend on the specific context and desired tone of your writing.