-jēəm noun
( plural basipteryg·ia -jēə)
Etymology: New Latin, from basi- + Greek pterygion fin, literally, small wing — more at pterygium
: a basal bone or cartilage forming a support of one of the paired fins of a fish:
a. : a large cartilage supporting the radialia in ganoids and selachians
b. : a large bone supporting the rays of a pelvic fin in teleosts
c. : the posterior member of a group of three such supporting elements in certain fishes — compare mesopterygium , metapterygium , propterygium