malform

To malform means to form badly or to give something an abnormal shape. It is used most often when talking about physical development, especially in medicine. For example, if a baby is born with a malformed heart, the heart did not develop in the usual or healthy way before birth.

The word comes from mal- meaning "bad" and form meaning "shape." Because of that, it usually points to a problem in structure rather than just appearance. A malformed limb, organ, or bone is not simply unattractive; it has developed in a way that is not normal. This is why the word often appears in medical writing or careful descriptions of birth defects and abnormal growth.

Outside medicine, the word can sometimes be used more broadly for anything shaped badly or formed the wrong way, but that use is less common. It is also much more common to see the adjective malformed than the verb malform itself. In most contexts, the word has a negative sense, suggesting damage, defect, or abnormal development, even if the thing can still function to some degree.

So, in everyday understanding, malform points to a failure to take the proper shape. Whether you are describing an organ, a limb, or another physical structure, the word suggests that something formed in the wrong way rather than simply looking unusual.