
1) Auditory system
Found on
https://www.crosswordclues.com/clue/round-window

The round window is one of the two openings into the inner ear. It is closed off from the middle ear by the round window membrane, which vibrates with opposite phase to vibrations entering the inner ear through the oval window. It allows fluid in the cochlea to move, which in turn ensures that hair cells of the basilar membrane will be stimulated ...
Found on
http://en.wikipedia.org/wiki/Round_window

(from the article `ear, human`) The ossicular chain not only concentrates sound in a small area but also applies sound preferentially to one window of the cochlea, the oval window ... ...otic capsule of the inner ear. It has two small openings, or fenestrae, one above the other. The upper one is the oval window, which is closed by ... ...
Found on
http://www.britannica.com/eb/a-z/r/71

Image: © 1998 Wadsworth Publishing Co./ITP A membrane-covered opening between the middle ear to the inner ear. It lies below the oval window. Pressure waves transmitted through the perilymph in the cochlea are released into the middle ear through the round window.
Found on
http://www.daviddarling.info/encyclopedia/R/round_window.html

Fenestra of the cochlea; an opening in the medial wall of the middle ear leading into the cochlea. ... (12 Dec 1998) ...
Found on
http://www.encyclo.co.uk/local/20973

a round opening in the middle ear covered by the secondary tympanic membrane; called also cochlear window and fenestra cochleae.
Found on
http://www.encyclo.co.uk/local/21001

Type: Term Definitions: 1. an opening on the medial wall of the middle ear leading into the cochlea, closed in life by the secondary tympanic membrane. Synonyms: fenestra cochleae, cochlear window, fenestra of the cochlea, fenestra rotunda
Found on
http://www.medilexicon.com/medicaldictionary.php?t=99936

Round window: The membrane separating the inner ear and middle ear. The tympanum (eardrum) separates the middle ear and outer ear.
Found on
http://www.medterms.com/script/main/art.asp?articlekey=33103

A round, membrane-covered opening between the middle and inner ear, directly below the oval window; also called the cochlear window.
Found on
http://www.mhhe.com/biosci/abio/glossary.mhtml

Former name of the cochlear window.
Found on
https://academy.allaboutbirds.org/bird-academys-a-to-z-glossary-of-bird-ter

membrane separating the middle ear and inner ear.
Found on
https://www.stanfordchildrens.org/en/topic/default?id=glossary---ear-nose-a
No exact match found.