侏儒症（Dwarfism）是指人、动物或植物极端矮小的一种状态。以前在日常生活和医学上，任何类型的人明显矮小都可称为侏儒症。而今，这一名词只限于极端矮小且身体不相称的人，通常是由于骨或软骨发育的遗传性疾病。相反，由于内分泌或营养异常而致的相称性的身材矮小，不再被称为"侏儒"。其中一个例子是"生长激素缺乏症"，曾经被称作"垂体性侏儒症".
就人类来说，经常是因为4p16.3 染色体位置的FGFR-3 (纤维芽细胞生长因子第三号接受体，fibroblast growth factor receptor-3)基因发生突变而造成。

Dwarfism (UK: /ˈdwɔːfɪsəm/; US: /ˈdwɔːrfɪzəm/) occurs when an individual organism is short in stature resulting from a medical condition caused by slow growth. In humans, dwarfism is sometimes defined as an adult height of less than 4 feet 10 inches (58 in; 147 cm). Dwarfism can be caused by more than 300 distinct medical conditions, such that the symptoms and characteristics of individuals with dwarfism vary greatly. Disproportionate dwarfism is characterized by one or more body parts being relatively large or small in comparison to those of an average-sized adult, with growth variations in specific areas being apparent. In cases of proportionate dwarfism, the body appears normally proportioned, but is unusually small.