A corm, bulbo-tuber, or bulbotuber is a short, vertical, swollen underground plant stem that serves as a storage organ used by some plants to survive winter or other adverse conditions such as summer drought and heat (perennation).

The word cormous is used to describe plants growing from corms, in analogy to the use of the terms "tuberous" and "bulbous" to describe plants growing from tubers and bulbs.