WordNet sense 1 (experiencing or marked by or expressing sorrow especially that associated with irreparable loss):

sorrowful

WordNet sense 2 (very sad; especially involving grief or death or destruction):

tragic

WordNet sense 3 (showing pensive sadness):

pensive, wistful

WordNet sense 4 (characterized by or causing or expressing sadness):

melancholic, melancholy

WordNet sense 5 (filled with or evoking sadness):

doleful, mournful

WordNet sense 6 (causing or suggestive of sorrow or gloom):

depressing, gloomy

WordNet sense 7 (bad; unfortunate):

deplorable, distressing, lamentable, pitiful, sorry

WordNet sense 8 (having undesirable or negative qualities):

bad