discouraging
alarming
awing
black
bleak
chilling
daunting
demoralising
demoralizing
depressant
depressing
depressive
despondent
deterrent
deterring
disappointing
disconcerting
dismal
dismaying
dispiriting
displeasing
disquieting
dissatisfactory
down
dreary
fear-inspiring
fearful
fearsome
frightening
frightful
funereal
inadequate
incommensurate
insufficient
not good enough
oppressive
overawing
pessimistic
scaring
scary
somber
startling
unfulfilling
ungratifying
unsatisfactory
unsatisfying
appal
cheerless
daunt
disappoint
disastrous
disturb
frustrate
gratify
harrowing
humiliate
irksome
lamentable
regrettable
unfavourable
unpromising
unpropitious
unwelcome
heartening
smartening