1. Insusceptible of reform
   - irreclaimable, irredeemable, unredeemable 
2. Unrepentant and incapable of being reformed
   - unregenerate

See also: incorrigible, wicked

• feetfirst
• Fehling's solution
• Feifer
• feign
• feigned
• feigning
• feijoa
• feijoa bush
• feint
• feist
• feisty
• felafel
• Feldene
• feldspar
• Felicia
• Felicia amelloides
• Felicia bergeriana
• felicitate
• felicitation
• felicitous
• felicitously
• felicitousness
• felicity
• felid
• Felidae