-less BrE AmE ləs lɪs —In singing, a strong-vowelled form les is usual.
— Preference poll, British English (for the word careless, disregarding votes for -les and from respondents who do not distinguish ɪ from ə in this position): -ləs 74%, -lɪs 26%
▷ — faithless ˈfeɪθ ləs -lɪs , in singing -les