(1):

(n.) A simple podlike pericarp which contains several seeds and opens along the inner or ventral suture, as in the peony, larkspur and milkweed.

(2):

(n.) A small cavity, tubular depression, or sac; as, a hair follicle.

(3):

(n.) A simple gland or glandular cavity; a crypt.

(4):

(n.) A small mass of adenoid tissue; as, a lymphatic follicle.