1. A liquid that is pure, uncolored, and without added flavoring, chemicals, or other substances; typically referring to water or basic solutions
The doctor recommended drinking plain liquid to stay hydrated.
O médico recomendou beber líquido simples para se manter hidratado.
2. In medical or scientific contexts, a solution that lacks additives or pigmentation
Use plain liquid for the dilution process.
Use líquido simples para o processo de diluição.