Molar

Part of speech: noun, adjective

Pronunciation: /məʊlə(ɹ)/

Definitions

1. A large tooth at the back of the mouth used for grinding and chewing food
2. A tooth located in the back part of the mouth, primarily responsible for the grinding and crushing of food for digestion
3. A broad tooth located in the rear of the mouth used for crushing and grinding food ; connected with the mole unit or concentration in chemistry, such as molar solutions

Etymology: The tooth and the chemical unit share a surprisingly plain ancestor: Latin "mola", meaning millstone. Because a millstone grinds grain, the Romans applied the adjective "molaris" to the teeth that did the same job at the back of the mouth, and the word reached Middle English in that sense as "molar". The grinding idea is literal: the tooth is named for the stone, not for any resemblance in shape. The chemical sense is a much later and more modern development. It comes from "mole", the unit of amount of substance in chemistry, which took its name from the Latin "moles", meaning a mass or heap, and the adjective was formed by adding the suffix "-ar". So a molar solution is one with a given number of moles of solute per litre. The two senses thus meet only by coincidence of spelling: one reaches back to a millstone, the other to a heap of matter.

Synonyms: tooth, grinder, chewer, premolar, bicuspids