Seidion i-nírnaeth nîn, lû sui duinen nin gwathra.
I have saved up my tears, time like tide overshadows me.
The only known example of a linnod is Gilraen's Linnod, and since it is comprised of two lines of seven syllables each, Tolkien linguistics scholars have theorized that perhaps it means 'song of seven'. Like the rendering of Elvish verse into Westron using ann-thenath, it might be an established cultural meter or form of delivering poetry, just as English sonnets or the borrowed form of haiku from Japanese.
Even more literal translation:
Set aside for a purpose-I the-tears mine, time like high-tide waters me overshadows.
No one is this effing literal translation:
Seidia- (v; stem) becomes *seidion (v; first person singular present tense) To set aside, to appropriate to a special purpose or owner.
i (article; definite, singular) the
Nírnaeth (n; singular) derived from nír (n; singular)+naeth (n; singular) weeping, lamentation, gnashing of teeth; literally "tear-biting"
nîn (pronoun; first person singular possessive) my, mine
lû (n; singular) time
sui (conjunction) like/as
duinen (n; singular) flood, high tide
nin (pronoun; first person singular accusative [objective]) me.
gwathra- (v; stem) becomes *gwathra (v; third person/passive singular present tense) to overshadow, to dim, to veil, to obscure