Pectinate is a term used to describe certain insect antennae. The segments of pectinate antennae are longer on one side, giving each antennae a comb-like shape. Bipectinate antennae look like two-sided combs. The term pectinate derives from the Latin pectin, meaning comb.
Pectinate is just one of many morphological forms of insect antennae. See also:
Source: Borror and DeLong's Introduction to the Study of Insects, 7th Edition, by Charles A. Triplehorn and Norman F. Johnson