The term half-uncial or semi-uncial was first deployed by Scipione Maffei, Istoria diplomatica (Mantua, 1727); he used it to distinguish what seemed like a cut-down version of uncial in the famous Codex Basilicanus of Hilary, which contains sections in each of the two types of script. The terminology was continued in the mid-18th century by René Prosper Tassin and Charles François Toustain. Despite the common and well-fixed usage, half-uncial is a poor name to the extent that is suggests some organic debt to regular uncial, though both types share features inherited from their ancient source. See now: L. E. Boyle, “‘Basilicanus’ of Hilary Revisited,” in Integral Palaeography, with an introduction by F. Troncarelli, 105-17. Turnhout, 2001
Like uncial, half-uncial derived from Roman cursive, but now of a later, evolved type. It was first used around the 3rd century and remained in use until the end of the 8th century. The early forms of half-uncial were used for pagan authors and Roman legal writing, while in the 6th century the script came to be used in Africa and Europe (but not as often in insular centres) to transcribe Christian texts.
Read more about this topic: Uncial Script