An auditory cyst or vesicle; one of the simple auditory organs of many invertebrates, containing a fluid and otoliths; also, the embryonic vesicle from which the parts of the internal ear of vertebrates are developed.

the early stage of the innner ear.

(= otic vesicle) sensory placode which sinks into mesoderm to form spherical vesicle (stage 13/14 embryo) that will form components of the inner ear. (More? Senses Notes)