The preceding video shows all of Legolas’ lines of dialogue spoken in the Elvish language Sindarin in Peter Jackson’s Lord of the Rings adaptation. Whereas Quenya was heavily influenced by Finnish, Tolkien based Sindarin off of Celtic languages, in particular Welsh.
Unlike Quenya, Sindarin mostly lacks vowel endings, but does include the voiced stops b, d and g, which Quenya lacks.
Plurals in Sindarin are created by changing the vowels in a word, as in goose becoming geese and man becoming men in English. For example, when made plural, a becomes e in non-final syllables and e becomes i in final syllables, so the word adaneth, meaning mortal woman, becomes edenith when plural.
Like the Celtic languages it is based on, Sindarin also contains consonant mutations. This means that letters in certain words may change sound depending on the letter preceding them or their context in a sentence. For instance, in Sindarin, the letter b becomes v when preceded by the article i, which means the. For instance brethil, silver birch, would become i vrethel, the silver birch.
Some examples of words and phrases in Sindarin are:
Man le estach? What do you call yourself?
Pedich Edhellen? Do you speak Elvish?
The elvish hymn A Elbereth Gilthoniel in Sindarin.