Lamellate

Lamellate antennae end with nested segments.
Lamellate antennae end with nested segments. Wikimedia Commons user L. Shyamal, license cc-by-SA 2.5

Definition:

Lamellate is a term used to describe certain insect antennae. The term comes from the Latin lamella, meaning a thin plate or scale. In lamellate antennae, the segments at the tip are flattened and nested, so they look like a folding fan.

Lamellate is a common morphological form of antennae found in many insect groups. To see an example of lamellate antennae, look at a scarab beetle.

Lamellate 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