Quenya is the Elvish language Tolkien developed with strong inspiration from Finnish.
Within Tolkien’s fictional history, Quenya was associated especially with the High Elves, including the Noldor and Vanyar. Tolkien also called it “the language of the Eldar,” and its vocabulary and grammar were developed in considerable detail rather than being a few invented words.
Finnish influenced Quenya’s sound and structure, while Welsh strongly influenced the development of Sindarin, another major Elvish language. Tolkien revised both languages repeatedly throughout his life, so their forms can differ across drafts and published texts.
Quenya is sometimes described as the Elvish language without qualification, but Tolkien’s world contains several Elvish tongues. Sindarin is generally the more widely spoken Elvish language in the Third Age, whereas Quenya has a more formal and historical role. The distinction is important when identifying Tolkien’s languages precisely.