A nodule of stone having a cavity lined with mineral or crystal matter on the inside wall.
A space visible between cells, allowing free passage of light.
Any gap, break, hole, or lack in a set of things; something missing.
A language gap, which occurs when there is no direct translation in the target language for a lexical term found in the source language.
An absent part, especially in a book or other piece of writing, often referring to an ancient manuscript or similar.
A small blank space; a gap or vacancy; a hiatus.
A small opening; a small pit or depression, especially in bone.