Although stela and stele were used in antiquity for pillars and columns generally, and continued to carry that meaning when their use was revived in English archaeology and architecture in the 18th and 19th century, respectively, present usage usually distinguishes obelisks, columns, shafts (the body of a column between the capital and the pediment), etc., from stela and stele, which are used to refer to engraved slabs or small pillars.
The terms do sometimes refer to undecorated rocks when they have been raised by artificial means in prehistoric times, particularly when they are slab-like, but the large Neolithic menhirs are usually distinguished as are Chinese scholar's rocks or Taihu rocks, and other modern uses of upright stones as decoration or signage.
Stele is frequently pluralized irregularly as stelae, which is also used as a plural form of the more Latinized singular form stela. The anglicized Greek plural stelai has been used since the late 19th century but is less common than steles.