say it: KOWNT-luhs
countless is an adjective meaning "too numerous to be counted". It is pronounced /ˈkaʊntləs/ — KOWNT-luhs. 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.