pit ‧ i ‧ less /ˈpɪtɪləs/ BrE AmE adjective
1 . showing no pity and not caring if people suffer SYN cruel :
a pitiless tyrant
the pitiless bombing of Guernica
2 . literary pitiless wind, rain, or sun is very severe and shows no sign of changing:
a night of pitiless rain
—pitilessly adverb