fearsome (adj.)

• alarming
• appalling
• awe-inspiring
• awesome
• awing
• bashful
• chilling
• cowardly
• daunting
• deterrent
• diffident
• disconcerting
• discouraging
• disheartening
• dismaying
• disquieting
• dreadful
• fearful
• fearing
• formidable
• frightening
• frightful
• goosy
• intimidating
• jumpy
• menacing
• mousy
• nervous
• scary
• shaky
• shivery
• shrinking
• shy
• skittish
• startling
• terrible
• terrifying
• timid
• timorous
• trembling
• tremulous
• trigger-happy