The term "in-form" refers to a person or thing that is currently performing well, in good condition or in great shape. The antonyms for this word include "out of form" or "out of shape," which describe a person or thing that is not performing well and is in poor condition. Another antonym is "unfit," which means not suitable or not healthy enough to perform a certain activity. Additionally, "unwell," "sickly" and "ailing" are other antonyms that denote poor health or condition. These antonyms emphasize the opposite of being in great shape or form and suggest a negative state of being.