a ring-shaped life preserver.
The Hidden Histories Of “Humpty Dumpty,” “London Bridge,” And “Ring Around The Rosie”These hidden stories behind these three popular nursery rhymes may not be well known but they certainly make songs like "Humpty Dumpty" a little more interesting.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for ring buoy
And that ring-buoy and whip-line—have ye got it slung and ready to reeve off?The Viking Blood|Frederick William Wallace