1. Impossible to achieve
   - unachievable, unattainable, undoable, unrealizable

See also: impossible

• Senegal gum
• Senegalese
• Senegalese franc
• Seneka snakeroot
• senesce
• senescence
• senescent
• seneschal
• senga root
• Senhor
• senhora
• senile
• senile dementia
• senile psychosis
• senility
• senior
• senior chief petty officer
• senior citizen
• senior class
• senior high
• senior high school
• senior lecturer
• senior master sergeant
• senior moment
• senior pilot