It could be that the name literally means 'lambs' moor'. and is derived from the Old English words lambra and mor. It could also be the case that the name is Gaelic, and derived from lann barra mor, meaning 'level spot on the big height'. Early forms include Lombormore,Lambremore, Lambermora and Lambirmor.
Spanning the counties of Selkirk, East Lothian, and Berwick, the Lammermuirs extend from the Gala Water to St Abb's Head, and offer a traditional site for sheep grazing. The hills are nowhere especially high, the highest points being Meikle Says Law at 535 m (1,755 ft) and the Lammer Law at 528 m (1,732 ft); but steep gradients, exposure to the elements, and a lack of natural passes combine to form a formidable barrier to communications between Edinburgh and the Borders.
The hills are crossed by only one major road (the A68), which crosses the shoulder of Soutra Hill between Lauder and Pathhead, and is frequently closed by snow in winter. The main road linking Edinburgh to England (the A1) avoids the hills by following a circuitous route around the coast.
Crystal Rig Wind Farm is located on the hills.