ostiole

This term is used exclusively within biological and botanical contexts to describe specialized, minute openings. It carries a clinical, technical register and is never used in casual conversation to describe a general hole or gap.

In zoology, it specifically refers to the intake pores of sponges, while in botany, it describes the small opening of a nectary. Because it describes a specific anatomical structure, it is distinct from more general terms like pore or orifice.