畸形 (jī xíng) is a noun meaning 'malformation' or 'deformity'—a physical abnormality in shape, structure, or development, often present from birth or resulting from disease or injury. The first character 畸 (jī) means 'abnormal', 'irregular', or 'deviant', while 形 (xíng) means 'form', 'shape', or 'appearance'. Together, they literally convey 'abnormal form', emphasizing structural deviation from the typical or healthy standard.

This term is commonly used in medical, biological, and scientific contexts—such as describing congenital conditions (e.g., heart defects, limb abnormalities), developmental disorders, or even metaphorical distortions (e.g., 'distorted values'). It carries a neutral-to-clinical tone and is rarely used in casual speech; it’s more frequent in formal reports, textbooks, or health discussions. Unlike colloquial terms like 畸形儿 (jī xíng ér, 'child with a deformity'), 畸形 itself refers to the condition or feature—not the person—and should be used with sensitivity to avoid stigmatization.