1. A cavity filled with air: An aerocele is a cyst or tumor formed by air filling an adventitious pouch, such as laryngocele and trachecele.
2. A cyst that is benign, contains air, thin-walled and can be found in the lung; pneumocele: When Dr. Smart was examining Mrs. Long, he detected an aerocele which turned out to be a case of staphylococcal pneumonia.