Heidegger's Bible Handbook: Psalms: Inscription
1. The Inscription. ספר תהלים, the Book of Psalms. Ψαλμοὶ, the Psalms. Ψαλτήριον, the Psalter.
This book is inscribed ספר תהלים, βίβλος Ψαλμῶν (Luke 20:42; Acts 1:20), the Book of Psalms, of hymns, of praises, from its better part, inasmuch as they are for the most part ἐπαινετικοὶ/epainetic/laudatory. For, it is derived from חלל, to praise, to honor. In the place of תהלים, the Rabbis call it תלים by way of contraction. In Greek they call it Ψαλμοὺς, the Psalms, and Ψαλτήριον, the Psalter, from ψάλλω, to touch, or to strike with a slight motion, whence a ψαλτήριον/psaltery is an instrument, the sound of the plucking of which is properly called ψαλμὸς, a striking: and which Suidas makes the same as a Psaltery: but Athenæus in Book V, section 25, of Deipnosophistæ, writes that it was filled with strings by Alexander of Cythera, and thus perfected, and fully developed with all the notes. But the reason for the imposed name is thought to be sought from the practice of the Jewish Church. They were singing songs, principally in their Synagogues, and also privately at home, at the stroke of the lyre or psaltery.
 An instrument of ten to twelve strings with a sounding board.