say it: KOWNT-luhs
countless is an adjective meaning "too numerous to be counted". It carries one recorded sense.
too numerous to be counted
“countless hours”
“an infinite number of reasons”
“innumerable difficulties”
“the multitudinous seas”
“myriad stars”
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for countless come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.