Definitions for "Shema"
(Hear!) the first word of Deuteronomy 6:4, "Hear [ Shema], O Israel! The LORD our God, the LORD is one." In Judaism this verse is the supreme affirmation of God's oneness and uniqueness. Since at least the second century A.D. the Shema has consisted of three passages: Deuteronomy 6:4-9; 11:13-21; Numbers 15:37-41 plus the accompanying benedictions that were recited before and after the three passages.
first word of the verse beginning Shema Yisrael ("Hear O Israel..."), the daily declaration of faith in the Unity of G-d; see Siddur Tehillat HaShem, p. 46
the third passage in tefillin and the first passage in mezuzot (Deut. 6:4-9).