The name of Gandalf “in the South” (LotR/670). In one place, Tolkien intrepretted this name as Quenya, meaning “Mind Master(ship)”, a derivation of the roots √IN(ID) and √KAN (UT/400) from the word incánussë “mind mastership” (PE17/88, 155). Elsewhere he interpreted it as a name in the language of the Haradrim meaning “North-spy” (UT/399): see Eas. Incánus for discussion of its meaning in that language and of earlier forms of the name.
Conceptual Development: In his notes on Words, Phrases and Passages from the Lord of the Rings from the late 1950s or early 1960s, Tolkien indicated that this word was Latin, which Christopher Gilson (among others) pointed out meant “grey-haired” (PE17/88). This Latin term may be the original inspiration for this name.
incánus (*incánuss-), also incánussë, noun "mind mastership" (PE17:155), associated with Incánus as a name of Gandalf.