The phrase "canst do" means to be able to do something. The antonyms for "canst do" are "unable to do" or "incapable of doing." These antonyms convey a sense of limitation, inability, or disability. Other antonyms include "restricted from doing," "forbidden to do," or "not permitted to do." These antonyms can be used to describe a situation where a person is physically or mentally unable to accomplish a task or is prevented from performing a specific action due to legal, moral, or ethical reasons. In general, antonyms for "canst do" highlight the opposite of ability, freedom, and empowerment.