S. Argonui m.
The 8th chieftain of the Dúnedain (LotR/1038). The initial element of his name is the prefix ar(a)- “noble”. The remainder of the name might be the noun caun (in any of its various meaning) with the adjectival suffix -ui (as suggested by David Salo, GS/246, 342).
References ✧ LotRI; PMI
|ar(a)-||“noble, royal, high”|
|caun¹||“prince, chief, head”|
|-ui||“-ful, having quality, adjective suffix; possibility, suitability [as verbal suffix], *-able”|