lacuna

noun

• A small opening; a small pit or depression.
• A small blank space; a gap or vacancy; a hiatus.
• An absent part, especially in a book or other piece of writing, often referring to an ancient manuscript or similar.

  "Long lacunae in this inscription make interpretation difficult."

• Any gap, break, hole, or lack in a set of things; something missing.
• A space visible between cells, allowing free passage of light.
• A language gap, which occurs when there is no direct translation in the target language for a lexical term found in the source language.