From the 1910s to the 1970s, J.R.R. Tolkien worked at creating plausibly realistic languages to be used by the creatures and characters in his novels. Like his other languages, Sindarin was a new invention. In A Gateway to Sindarin, David Salo has created a volume that is a serious look at an entertaining topic.
A serious look at J. R. R. Tolkien's elvish tongue Sindarin, by means of its grammar, morphology, and history. Supplemental material includes a vocabulary, Sindarin names, and a glossary of terms.