Thalassian is the primary language of Sin'dorei and Quel'dorei (and by extension, of the Ren'dorei). It has both written and spoken equivalents. Individuals who are unfamiliar with the language's proper name may refer to it as High Elven.
Like Nazja, Thalassian is derived from the Darnassian language. Hence, Thalassian is closely related to Darnassian and there is some overlap between the two languages. Further Darnassian utterances may, therefore, have been preserved in modern Thalassian, in addition to those that are specified below.
So far, linguistic scholars have opted to err on the side of caution in documenting Darnassian terms and phrases that are also considered part of the Thalassian language. Certainly, this issue, however delicate, merits further research. Nevertheless, addressing a high elf or blood elf with a Darnassian-specific word or phrase can be considered offensive or at the very least rather foolish, and so the speaker must handle the situation with care.
Thalassian is one of the four known elven dialects.
Thalassian primer (official translations)
Here are a few common Thalassian phrases and words, for which the translations have been officially confirmed by Blizzard:
- Alar'annalas = Ranger Lord.
- Al diel shala = Safe travels.
- Ama noral'arkhana = Saved by magic.
- Anar'alah = By the light.
- Anar'alah belore = By the light of the sun.
- Anaria shola = Speak your business.
- Anar'endal dracon = By the breath of the dragon.
- Ann'da = Papa/Father.
- Anu belore dela'na = The sun guides us.
- Aranal = Rise.
- Bal'a dash, malanore = Greetings, traveler.
- Ban'dinoriel = Gatekeeper.
- Band'or shorel'aran — (Roughly) "Prepare to say farewell", spoken by Commander Sarannis, officially translated in the Chinese version of WoW.
- Bash'a no falor talah! = Taste the chill of true death! Sylvanas Windrunner (WC3)
- Belono sil'aru, belore'dorei = Shoulder your burdens well, child of the sun. Used to end the appointing ceremony of a ranger lord of the Farstriders.
- Belore = The sun, though can mean to uncover something hidden or unknown if used in Darnassian.
- Belore'dorei = "Child of the Sun"
- Doral ana'diel? = How fare you?
- Elor bindel felallan morin'aminor = Sleep forever in quiet serenity.
- Elu'meniel mal alann = May peace calm your heart.
- Felo'melorn = Flamestrike.
- Kim'jael = Little rat.
- Medivh = keeper of secrets. When used as a proper noun, Medivh refers to the last Guardian of Tirisfal.
- Minn'da = Mama/Mother.
- Quel'dorei = Children of noble birth, or the high elves.
- Quel'Serrar = High Blade.
- Quel'Thalas = High Home.
- Rea = And. Used to connect words of the same part of speech, clauses, or sentences, that are to be taken jointly.
- Ren'dorei = Children of the Void.
- Selama ashal'anore = Justice for our people.
- Shindu fallah na! = They're breaking through!
- Shorel'aran = Farewell.
- Sin'dorei = children of the blood. This can also be interpreted as "people of the bloodline".
- Sinu a'manore = Well met.
- Sunstrider = he who walks the day. When used as a proper noun, Sunstrider is the family name of the high elves' royal bloodline.
- Tal anu'men no Sin'dorei = "Death to all who oppose the children of the blood". Spoken by High Astromancer Solarian in Tempest Keep.
- Thas'alah = Light of the Forest.
- Thas'dorah = Valor of the Forest.
- Vendel'o eranu = Help me forget.
Untranslated words or phrases
- An'daroth — One of the three Ghostlands Darnassian spy encampments. Possibly Darnassian.
- An'owyn — One of the three Ghostlands Darnassian spy encampments. Possibly Darnassian.
- An'telas — One of the three Ghostlands Darnassian spy encampments. Possibly Darnassian.
- Anar'alash denal! — Said by Lor'themar Theron during H  One Last Grasp.
- Anu bala belore alon — Nethermancer Sepethrea.
- Aranal, ledel! — Prince Keleseth.
- Anara'nel belore — Kael'thas Sunstrider.
- Balamore shanal! — Kael'thas Sunstrider.
- Bandal! — High Nethermancer Zerevor.
- Belesa menoor! — High Nethermancer Zerevor.
- Bin dorei am'ovel. — Prince Taldaram.
- Diel fin'al. — High Nethermancer Zerevor.
- Elrendar — a Quel'Thalas river and a waterfall, both fed by a lake with the same name.
- Endala finel endal! — Nethermancer Sepethrea.
- Endorel aluminor — High Botanist Freywinn.
- Enshu-falah-nah, dorini. — Said by Sky Captain Swayze on the Spine of Deathwing. Possibly Darnassian.
- Falthrien — an arcane academy on Sunstrider Isle.
- Falithas — One of the runestones protecting Eversong from the plague.
- Felomin ashal — Kael'thas Sunstrider in Magister's Terrace.
- Quel'Danas — Island home of the dragonhawks and location of the Sunwell.
- Quel'Danil = High Vale. "Quel" means "High". Danil can be inferred from the name of the Highvale Vindicator, Highvale Sentry, Highvale Swiftblade, and the other removed NPCs of the lodge. It is translated as "High Peak" in the non-canon RPG.
- Quel'Lithien — A quel'dorei lodge in Eastern Plaguelands, and location of the Silvermoon City Register.
- Selama am'oronor! — Said by High Nethermancer Zerevor.
- Selama amor'anore! — Said by Gathios the Shatterer.
- Shalandis — An island off the coast of the western Ghostlands, headquarters of Darnassian spying missions against Silvermoon City.
- Shan'dor — One of the runestones protecting Eversong from the plague.
- Tel'thas — Dagger of the Blood King.
- Thalas'din belore — inscribed on [Fal'inrush, Defender of Quel'thalas], most likely translated as 'Home of the Sun'.
Adapted from WoWPedia