Real Dictionary

water wings
plural noun: Water wings are plastic rings filled with air that people who are learning to swim wear on their upper arms to help them float.

water wings in American English
a device, inflated with air, used to keep one afloat as while learning to swim: it is shaped somewhat like a pair of wings and is worn under the arms
plural noun: an inflatable contrivance shaped like a pair of wings, usually worn under the arms to keep the body afloat while one swims or learns to swim

water wings in British English
plural noun: an inflatable rubber device shaped like a pair of wings, which is placed round the front of the body and under the arms of a person learning to swim