There are several known Quenya words for 'song' in the published
corpus. All of them begin with the voiced dental approximant written with
_l_ in Latin spelling.
_líre_ seems to be derived with lengthening of the stem vowel from LIR-
'sing, trill' (V:369), whence comes also the verb _lir-_ 'chant, sing'
(V:359, 369). Both the context in which _líre_ is used (referring to
_Namárië_, which Tolkien sang as a Gregorian chant) and its cognates
(_laire_ 'poem' (V:359), _glin_ 'to sing, recite poem') imply that it was
used around the meanings of 'a lyrical verse; poetry' and also 'a chant'.
_linde_ is glossed in the Etymologies as 'song, air, tune' (V:359, 369). It
is probably derived with medial fortification from GLIN-, whence e.g.
_lindo_ 'singer, singing bird' (V:369) and _lindele_ 'music'. Thence also
*_lindale_ 'music, song' (LR:350). It is used in the place name
_Ondolinde_ 'Stone Song'. These contexts imply that _linde_ was used
to refer to 'the melodious sounds made by certain creatures',
while_lindale_ to 'the art of singing, or the body of music to be sung'.
The context of *_linwe_ 'song' (<_Eärendillinwe_, VII:103) implies that it
was used for the first meaning of 'song': 'a brief musical composition
that is either intended to be sung or is able to be adapted for singing'.
So there we have it, four distinct words covering the four meaning of
English 'song' in Quenya. Quite convenient.
Petri Tikka Helsinki, Finland