countless

adjective

count·​less ˈkau̇nt-ləs 

: too numerous to be counted : myriad, many

countlessly adverb

Synonyms of countless

• many
• numerous
• innumerable
• numberless

Examples of countless in a Sentence

There are countless reasons why that would not be a good idea.

I've been there countless times.

Recent Examples on the Web

Karuna moved into Boston Children’s Hospital’s pediatric ICU, where Amisha and I spent countless sleepless nights. — Raj Panjabi, Time, 13 Oct. 2026

In an era where information is a market commodity capable of causing countless problems or yielding numerous benefits, a communicator’s negotiating ability and strategy are crucial. — Expert Panel®, Forbes.com, 13 Oct. 2026

But Dawood says that the Titanic was one of countless interests for Suleman sparked by their family travels. — Julia Buckley, CNN Money, 13 Oct. 2026

As Halzen and countless other scientists have found over the years, Antarctica’s extreme conditions serve as a crucial gateway to understanding some of the greatest mysteries of the cosmos. — Daniella McCahey, The Conversation, 12 Oct. 2026

Word History

First Known Use

1593, in the meaning defined above

Kids Definition

countless

adjective

count·​less ˈkau̇nt-ləs 

: too numerous to be counted : innumerable