Simple Definition of countless
: too many to be counted : very many
Examples of countless
There are countless reasons why that would not be a good idea.
I've been there countless times.
First Known Use of countless
COUNTLESS Defined for Kids
Definition of countless
: too many to be counted <countless grains of sand>
Seen and Heard
What made you want to look up countless? Please tell us where you read or heard it (including the quote, if possible).