Definitions

1. adjective

most wet or driest, or most flowing with water, as a place, or most capable of running or flowing with water.

“The runniest part of the track was where the rain had made it slippery.”

2. comparative

comparing two things, with the first being more wet or driest, or more capable of running or flowing with water.

“The runniest road in town is not as runniest as the one in the neighboring city.”