The "orn" in Aragorn means "tree." This name radical is often preceded in Sindarin by a "g" when the preceding element ends in a vowel, hence "ara" and "orn" becomes Aragorn. Given the Elvish emphasis on nature and the reverence and symbolism of trees in Elvish and Numenorean culture, Aragorn (High/Noble Tree) would be a pretty posh name.
With all due respect to the lore, I believe that Tolkien based the name Aragorn on real etymology: Ara-'Of royalty' (or to that effect), and -gorn 'seed' (or to that effect). This interpretation of 'Royal Seed' is also poetic in the plot, as Aragorn has to grow into kingship 'of the white tree'.
In a note associated with the Appendices Tolkien appears to explain this name as meaning 'Kingly Valour', but later in Words, Phrases And Passages he notes 'Ara(n)gorn = 'revered king' with the second element connected to a base NGOR 'dread' used in a sense of reverence, majesty. But yet in another note (same source) Tolkien asks himself: 'What is gorn in Aragorn, Celegorn. Kurna-... Aragorn is [? Simply modeled (on)? Ending] of Arathorn, Celegorn etc.... for [? Pure] Argorn.'And yet again in a very late source [letter 347, dated 1972], Tolkien explains: '5. Aragorn etc. This cannot contain a 'tree' word (see note).* 'Tree-King' would have no special fitness for him, and it was already used of an ancestor. The names in the line of Arthedain are peculiar in several ways; and several, though S. In form, are not readily interpretable. But it would need more historical records and linguistic records of S. Than exist (sc. Than I have found time or need to invent!) to explain them.'Tolkien goes on to generally explain ara- as probably derived from cases where aran 'king' lost its n phonetically (as Arathorn), ara- then being used in other cases. In the end, in this letter [again noting the late date of 1972] JRRT does not specifically explain Aragorn's full name.
To shoot a couple of mistakes straight off this world:In Parma Eldalamberon issue 17, page 113, Tolkien states Aragorn means "revered king", from ara- "royal" and ngornâ "revered, dreaded". No valour, no trees. The name is pronounced, as clearly evident from Appendix E: Ah-(as in "say aaah" but a bit shorter) -rh- (a trilled r) -ah- (see previous) -go- (as in "gold") -rh- (see previous) -n (no comment) No Air, no Er, no Arrr.
Aragorn means, literally, "Lord of the Tree" or "Noble Tree". Ara - noble, g-augmentive prefix, orn- tree. The Languages of Tolkien's Middle Earth. Noel Ruth S.
The book 'Languages of Middle-earth' is highly inaccurate. According to latest information, the meaning is 'Royal Valour' which has been already proposed so I'd vote for it.
Ara- meaning noble or kingly, and the lenited Sindarin "g'orn" meaning 'of the tree', an obvious referral to the White Tree of Gondor. As earlier commented, 'gorn' also means warrior, which also fits in with Aragorn's name.
Aragorn: means "Lord of the Tree" (Sindarin) ar= "high" "royal" "noble" g= augmentive prefix orn= "tree" - this word is found in other names such as Celeborn (Tree of Silver) and Ornendil (Lover of Trees) *info taken from 'The Languages of Tolkein's Middle Earth' by Ruth S. Noel and from the Silmarillan