Today some friends and I started wondering why the small mats you might place under mugs and glasses are called coasters. Do they have anything to do with coasts, and if not, where does the word come from?

According to Wiktionary, the word coaster come from coast +‎ -er, and is possibly related to the Middle English coster (ornamental wall or bed hanging), which comes from the Anglo-Latin costera (side, coast, curtain).

The word has a number of different meanings:

• one who coasts
• Something that coasts (eg a sled or toboggan)
• a merchant vessel that stays in coastal waters
• a sailor who travels only in coastal waters
• a person who originates from or inhabits a coastal area
• a small piece of material used to protect the surface of a table, upon which one places cups or mugs
• a small tray on wheels, used to pass something around a table

According to the Online Etymology Dictionary, coaster was first used in English in the 1570s to mean “one who sails along coasts”, and was used to refer to boats that sail in coastal waters from the 1680s.

It was used to refer to a bottle-coaster, or “low, round tray used for a decanter”, from 1874. Such a tray was originally on wheels and coasted around the table to each guest in turn. Which is possibly the origin of the name. It was being uesd to refer to a drink mat by the early 20th century.

Such things are called beer mats in pubs. What are they called in other languages?