say it: THAWT-luhs
thoughtless is an adjective meaning "showing lack of careful thought". It carries 2 recorded senses.
showing lack of careful thought
“the debate turned into thoughtless bickering”
without care or thought for others
“the thoughtless saying of a great princess on being informed that the people had no bread; `Let them eat cake'”
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 thoughtless 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.