Related Clues:

• Murmur in a cat cafe
• Cat's sound of self-relaxation
• [I'm a happy cat]
• Contented cat's communication
• Happy tabby's sound
• Ideal engine sound
• Noise made by cat’s pursuer girl’s seen off
• Sound from a 91-Down
• Happy cats do this
• Sound of feline contentment
• (Belly rubs ... warm milk ... what a dream!)
• Express pleasure in almost virtuous manner at last
• Feline rumble
• Low vibrating sound
• Satisfied Siamese's sound