Synonyms for Cheerless (same or very similar meaning)
WordNet sense 1 (grave or even gloomy in character):
melancholy, somberWordNet sense 2 (causing dejection):
blue, dark, depressing, disconsolate, dismal, drab, dreary, gloomy, grim, dispiritingWordNet sense 3 (lacking cheer; depressing):
uncheerfulFrom the ODE community, based on WordNetadd/edit