The antonyms for the word "sings out" include mutters, whispers, mumbles, speaks softly, and murmurs. These words describe a quieter way of speaking or uttering sound, rather than projecting one's voice loudly and clearly. The opposite of singing out can also be expressed through words such as hush, silence, and quiet, which imply the absence of sound entirely. Additionally, the concept of "singing out" can be flipped to refer to an internal or subdued expression of emotion or thought, which can be described using adjectives such as repressed or muted. Overall, the antonyms for "sings out" encapsulate a range of ideas relating to volume, articulation, and intensity of sound.