Definition of "purr"

There was no one at home but a black cat, who was sitting quite content and purring on the hearth[.]

1886, Peter Christen Asbjørnsen, translated by H.L. Brækstad, Folk and Fairy Tales, page 278

"This is Cindy," she purred again, flashing a smile of perfect white teeth surrounded by full red lips.

2008, C. E. Osborne, Black Gold Death in the Sun, page 12

Beverly passed the city limits sign with the Porsche's motor purring contentedly after its two hundred and fifty-mile romp.

2001, E. C. Craver, Last Reunion, page 159

Instead, the tiger looked around, and gave a purr, and then a growl. What did that mean? The man could not tell. Then the tiger just flung upon the man some of the sand from the side of the hollow.

1918, Sarath Kumar Ghosh, The wonders of the jungle - Volume 2, page 113

The trill of her purr echoed inside his mouth when he kissed her again. Clutching at his shirt, her fingers traveled the muscles in his back.

2006, Brenda Williamson, Wolverton Blood, page 53

I sat still in the car and listened to the soft purr of the engine and my beating heart. Then slowly, and as silently as possible, I drove the car back to camp.

1997, Susan Wood, A Fly in Amber, page 191