• (n.) A process of bone formation in which ossification takes place in the perichondrium and either surrounds or gradually replaces the cartilage.
(ek″to-sto´sis) ossification beneath the perichondrium of a cartilage or the periosteum of a bone.
Ec`tos·to'sis noun [ New Latin See Ect- , and Ostosis .] (Physiol.) A process of bone formation in which ossification takes place in the perichondrium and either surrounds or gradually replaces the cartilage. 
Type: Term Pronunciation: ek′tos-tō′sis Definitions: 1. Ossification in cartilage beneath the perichondrium, or formation of bone beneath the periosteum.
Ectostosis is a process of bone formation in which ossification takes place in the perichondrium and either surrounds or gradually replaces the cartilage.