The phrase "flat sole" refers to a type of shoe or footwear that doesn't have a high or raised heel. It means that the bottom part of the shoe is completely flat, providing even support for the entire foot.
Sentences with «flat sole»
When outside will be very hot the designers advise us to wear flat sole sandals. (howomen.com)
There hard, flat sole gives you a stable base for your lifts. (fitnesscrest.com)
A growing popularity have shoes with flat soles and pointy toe. (howomen.com)