Comes from an old French word 'Andier' which was still used in many inventories. They were utensils made of iron with one placed each side of the hearth and are therefore usually listed in pairs. They were used for supporting wood when burning in a fireplace and the term andiron was generally used to describe an ornamental form of fire dog. Andirons therefore come in a large variety of sizes and shapes.
Dictionary of Traded Goods and Commodities, 1550-1820 (2007)
[lawn yrons; handiron; awndeyrone; aundyrone; aundiron; aundiorn; aundiarn; aniron; aniorn; angrane; angraine; angiers; angeron; anger; angarn; andyron; andrarn; andirone; andiro'; andirn; andiorn; andior; andiern; andian]
From Dorchester Inventories
(Left) circa 1650 : (Right) circa 1680
Decorative Andirons from about 1670 - front and side view
late 17th Century
'17th Century Firedogs'