The terms Olvar and Kelvar literally meant, respectively, "growing things rooted in the earth" and "living things that move"; in other words, the plants (and Fungi) and animals of Arda.

The Kelvar were sometimes divided in the bats and birds, water animals, Potili (insects and spiders), Rávatsar (amphibians and reptiles), Lassanakûni (leaf-eaters including Cattle, goats, sheep as well as wild deer), riding and draft animals (including horses and ponies), apsanakûni (meat eaters including bears, cats, dogs and wolves) and other dangerous animals.

The Olvar were sometimes divided into trees, other plants and fungi. Both types of living things included the Uvanimor or Monsters of Morgoth.