small accumulation of liquid, usually water, on a surface

A puddle is a small mass of liquid, usually water, uncontained on a surface. It can form either in depressions in the surface, or directly upon the flat surface, held together by surface tension. A puddle is generally considered to be small enough to step over or shallow enough to walk through, and too small to traverse with a boat.

A puddle in a forest clearing
A water puddle on a Danish beach

Puddles commonly form during rainstorms, and can cause problems for transport, especially when combined with cold conditions to form patches of ice, which are highly slippery and difficult to see.