§ Ammalas >> Amaldor >> Amroth (TI:223)
By the time of 1968 Tolkien translates Amroth as ’upclimber, high-climber’ (UT:245) because he had supposedly introduced the habit of living on telain (flats) up in the trees among the Galadhrim. Thus the initial element must be am- ’up’ from AM2-, also √AM ’go up’ (PE17:146). For the second element Christopher Tolkien cites rath- ’climb’ (UT:255), whence also rath, applied in Númenórean Sindarin to longer road-ways and streets of Minas Tirith, as Rath Dínen ’the Silent Street’. In The Etymologies N. rath ’course, river-bed’ is derived from RAT- ’walk’. However, according to a different conception Amroth and Nimrodel cannot be fully explained in Sindarin, though fitting it in form (UT:257). Similarly Haldir, cerin, caras, Orophin, Legolas, Thranduil, Amroth, Nimrodel, are suitable to Sindarin sounds and patterns, but are not clearly etymologizable as Sindarin (PE17:51). However, Nimrodel is translated several times (see 2.25).
In any case it seems that the early names of Amroth also show the same prefix am- ’up’. In Ammalas it could be the extended variant amba- with -mb- > -mm- and the final element -las may be lenited N. lhass ’leaf’ (LAS1-) or glas ’joy’ as in the name Borlas (GÁLAS-).
In Amaldor the final element -aldor may be lenited galdor, itself appearing as a personal name from GALAD- ’tree’; the compound thus meaning something like *’person up on the tree’.