The English language is wide and varied, and as such, there are many words that can be used interchangeably with the word "level." Some common examples include "flat," "even," "uniform," and "constant." "Smooth," "steady," and "regular" are other synonyms that come to mind when describing something level. In a more context-specific manner, one could consider "horizontal" or "grade" if pertaining to a surface, or "standard" or "equal" if used in a comparative sense. Synonyms can help expand vocabulary and add versatility to one's writing and speech, making it important to learn as many as possible.