n. a small sharp-pointed tip resembling a spike on a stem or leaf
n. the part of a book's cover that encloses the inner side of the book's pages and that faces outward when the book is shelved
n. a sharp rigid animal process or appendage; as a porcupine quill or a ridge on a bone or a ray of a fish fin
n. 背骨, 脊柱, 尖刺
[医] 脊柱; 棘, 刺; 马蹄嵴