Early Noldorin
alfuilin
noun. large white sea-bird, albatross, †swan
There are more words but they are from Tolkien's earlier conceptional periods. Tolkien likely changed these words as he evolved the aesthetics and completeness of the languages. You may even find languages that Tolkien later rejected. Do not mix words from different time periods unless you are familiar with the phonetic developments.
Below: Tolkien's Late Period (1950–1973). These are from Tolkien's late conceptual period — his most settled forms of the languages. Prefer these over the earlier ones above when composing new text.
Sindarin
alfuil
noun. large white sea-bird, albatross, †swan
The noun ᴱN. alfuilin was “used of several large white seabirds, especially the albatross” in the Early Noldorin Dictionary of the 1920s, an elaboration of ᴱN. alf “swan”. In the Gnomish Lexicon of the 1910s, G. {alcothil >>} alfuil simply meant “swan” (GL/19), and the word alfuilin appeared with that gloss in a couple of other word lists (PE13/109, PE13/136) before becoming “albatross”.
Neo-Sindarin: I’d adapt this word as ᴺS. alfuil “albatross, large white seabird” for purposes of Neo-Sindarin, perhaps originally with the sense “✱swan of the seaweed”.