egg cosy

noun

noun

A small cover made of wool or other material and designed to be placed over a boiled egg to keep it warm.

You lucky girl! Granny's knitted you an egg cosy for your birthday!
And when whe woke again he reappeared in a plastic incubator wearing an absurd little knitted cap like an egg cosy.2017, Fiona Farrell, Decline and Fall on Savage Street, →ISBN, page 194:

Entry derived from the Wiktionary, under licence CC BY-SA 4.0 — list of authors.