Dictionary.net

(F.), Hilum, improperly Hilus, the black spot on the top of a bean.' A name given by some writers to a small blackish tumour, formed by the protrusion of the iris through an opening in the transparent cornea, so called from its comparison with the hile or black mark presented by the vicia faba at one of its extremities. In Botany, the Hile or Hilum is the cicatricula of a seed, which indicates the place by which it was attached in the cavity of the pericarp. It is the umbilicus of the seed. The fissure of the spleen, kidney, lung, ovary, &c., is, also, called Hilus. See Porta.