Bulla
gen. and pi. bullae
1. A large blister appearing as a circumscribed area of separation of the epidermis from the subepidermal structure(subepidermal bulla) or as a circumscribed area of separation of epidermal cells (intraepidermal bulla) caused by thepresence of serum, or occasionally by an injected substance.
2. [NA] A bubble-like structure.