say it: ROO-fuhl
rueful is an adjective meaning "feeling or expressing pain or sorrow for sins or offenses". It carries one recorded sense.
feeling or expressing pain or sorrow for sins or offenses
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 rueful 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.