IPA: /ˈpɛrɪˌstoʊm/
KK: /pɛrɪˈstoʊm/
A ring of tooth-like structures that surrounds the opening of a moss capsule or the area around the mouth of some invertebrates.
The peristome of the moss capsule helps in the dispersal of spores.
Peristome → It is formed from "peri-" (meaning around) and "stoma" (from Greek, meaning mouth or opening). The word refers to a structure that surrounds an opening or mouth, particularly in botanical contexts.
Think of something that is 'around' ('peri-') an 'opening' ('stoma') — that's why peristome refers to a structure surrounding an opening.