a mass of six-sided wax cells built by honeybees in their nest to contain their brood and stores of honey

any cellular structure resembling this, or one riddled with cavities

The whole rock was a honeycomb of sepulchres — H Rider Haggard

the second stomach of a cow or other ruminant mammal, or tripe prepared from it

to cause (a structure) to be chequered or full of cavities like a honeycomb

to burrow or penetrate into every part of (a structure) or riddle it with holes

The government is honeycombed with spies — T H White