bed

Bed is one of the oldest, plainest words in English — pure Germanic, from Old English bedd, with cousins across the Germanic languages (German Bett, Dutch bed). It never passed through Latin or Greek; it has always just meant a place to lie down. That homely origin is exactly why its compounds are so easy: there is no buried metaphor, only the everyday idea of a flat base you rest on.

The key to the whole family is realizing that bed has always carried two linked senses at once:

1. the furniture you sleep on — bed, bedroom, bedclothes, bedding
2. any flat base or layer something rests on — riverbed, flowerbed, seabed, bedrock

The second sense is older and broader than people expect. Long before mattresses, a 'bed' was simply a prepared patch of ground — which is why a gardener still plants in a flowerbed, a river runs over its bed, and oysters grow on a bed of the sea. The thing rests on a flat, prepared base. That is the root idea.

From there the compounds fall out naturally:

- bed + room → bedroom: the room with the bed
- bed + clothes → bedclothes: the coverings on a bed
- bed + sit → bedsit: (British) a single room you both sleep and sit in
- sea + bed → seabed: the floor of the sea
- bed + rock → bedrock: the solid rock layer beneath the soil — and, figuratively, the firm foundation of anything
- em- (into) + bed → embed: to fix something firmly into a base layer, like a stone set into concrete

Notice how bedrock and embed both lean on the 'base layer' sense, not the furniture sense. When you embed a journalist with troops, or embed a video in a webpage, you are pressing it into a surrounding base — the same image as a fossil embedded in rock. The furniture and the foundation are two faces of one simple idea: a steady surface that holds something up.