- fensterA geologic structure formed by erosion or normal faulting on a thrust system; a tectonic window.
- fenestraAn opening in a body, sometimes with a membrane.
- fenestraneAny hydrocarbon consisting of a central carbon atom connected with single bonds to four other carbon atoms each of which is connected to two of the others by a chain of carbon atoms; any derivative of such a compound.
- fenestronA protected tail rotor of a helicopter, operating like a ducted fan.
- fissula ante fenestramA small, connective tissue-filled cleft in the temporal bone, located just anterior to the oval window in the inner ear, that acts as a permanent, narrow pathway between the middle ear and the vestibule.