cleisto-, cleist-, clisto-, clist-, cli-, clei-

(Greek: closed, shut)

1. A condition in which the foramen ovale of the heart fails to close.
2. An opening in the oval foramen of the heart.
3. A reference to the patency (opening) of the foramen (small opening) ovale of the heart.

In the fetal heart, the foramen ovale allows blood to enter the left atrium from the right atrium.

Applied to certain small inconspicuous permanently closed flowers, adapted for self-fertilization, occurring in various plants (e.g. Oxalis Acetosella, different species of Viola, etc.) on the same individuals as the normal larger brightly-colored flowers, which in such cases are either cross-fertilized or barren.
cleistophobia, cleithrophobia (s) (nouns); cleistophobias, cleithrophobias (pl)
An intensive fear of being in closed places or of being locked in some small space: There are people who are afflicted with cleistophobia and cannot tolerate being in a car, in a train, in a street car, or in a room in which they cannot open a window or the door.
A plant with closed spherical ascocarp.
ombrocleistogamic (adjective), more ombrocleistogamic, most ombrocleistogamic
Relating to flowers that stay closed whenever it is raining and within which self-pollination is occurring.
ombrocleistogamy (noun) (no plural)
Species of plants that have blossoms that are closed when it is raining.
physoclistous (adjective) (not comparable)
Referring to fish which have air bladders disconnected from the alimentary canal: The swim bladders or gas bladders of the physoclistous fish, but not cartilaginous fish like sharks and rays, are not affixed to the esophagus.
A reference to plants in which self-pollination takes place within flowers that remain closed because of abnormally cold conditions.