Answer: gravest

AnswerCrossword Clue
GRAVESTMost serious.
GRAVESTMost ominous.
GRAVESTMost somber
GRAVESTLike a worst-case scenario
GRAVESTLeast merry
GRAVESTMost serious
gravestauthoritative weighty
gravestGRAVE, extremely serious
gravestw-pitched in sound
gravestserious or solemn
gravestab in color somber
gravestimportant
gravestthe variety indicated by a grave accent