Drainable is a term that is often used when referring to areas that can be emptied or cleared out easily. Synonyms for the word could include "clearable," "emptiable," "evacuable," or "depletable." Other synonyms might include "dischargeable," "run-off," "liquidatable," or "permeable." Each of these synonyms carries a slightly different connotation, but all could be used to describe an area or system that can be emptied out or drained. Whether referring to a drainable lake or a drainable fuel tank, these terms can be useful when trying to describe how a system or area can be managed or emptied when needed.