The fictional language spoken by the Ents in J.R.R. Tolkien’s legendarium is Entish.
Entish is the language of the tree-like Ents of Fangorn Forest. Tolkien presents it as extremely slow, elaborate, and difficult for other peoples to learn. An Ent may spend a long time deciding whether a name is appropriate, reflecting the Ents’ patient and ancient outlook.
In The Lord of the Rings, Treebeard explains that Entish has no quick word for things that do not belong to the Ents’ own world. The Ents also learn some words from other languages, including the names of their wives. Entish should not be confused with Quenya or Sindarin, which are Elvish languages.