Calkin n. : A calk on a shoe. See Calk, n., 1.

Example:
Is Macully Calkin at the funeral to remember all the abuse he took from Michael Jackson?

Taxonomy
tree, fusc, Neil Calkin, rational number, Herbert Wilf, vertex, diatomic, vertices, fraction, sum, representations, fraction a/b, formula, 2n, n + 1, expression, free encyclopedia, breadth-first traversal.

Defination from the web:
Calkin–Wilf tree is a tree in which the vertices correspond 1-for-1 to the positive rational numbers. ... The description here is dual to the original definition by Calkin and Wilf, which begins by defining the child relationship and derives the ...