Keithan appears to be an elaboration of Keith, a Scottish place and clan name linked to woods or forest.
Keithan is a creative expansion of the Scottish surname-turned-given-name Keith, which derives from a Brythonic Celtic place name — likely *coed*, meaning "wood" or "forest" — found in several Scottish localities, most notably the town of Keith in Moray. The Keith family was one of the most powerful aristocratic dynasties in medieval Scotland, serving as hereditary Great Marischal of Scotland from the twelfth century onward, and their name passed into the Scottish and later broader English-speaking naming pool as a given name during the nineteenth and twentieth centuries.
Keith enjoyed peak popularity in the mid-twentieth century, borne by musicians (Keith Moon, Keith Richards), athletes, and a generation of English-speaking men. Keithan represents a generational reimagining of that heritage — taking a name that peaked and began to feel dated and extending it with a Gaelic-inflected suffix (*-an*, a common diminutive and masculine marker in Irish and Scottish names) to create something that feels simultaneously rooted and contemporary. This pattern of revitalizing familiar names by adding suffixes or altering endings is a recognizable feature of American naming culture, particularly from the 1990s onward, when parents sought distinctive names that still carried phonetic familiarity.
Keithan sits in the company of names like Caithan, Kaelan, and Brennan — names that feel Celtic in texture without requiring deep genealogical justification. It is a name for parents who want the forest-and-stone feel of Scottish heritage with a fresher silhouette.