Definitions:

1. not capable of occurring or being accomplished or dealt with adjective
   • an impossible dream
2. something that cannot be done noun
   • The assignment verged on the impossible.
3. used of persons or their behavior adjective
   • impossible behavior

Synonyms:

• inconceivable
• out of the question
• unacceptable
• unimaginable

NearBy Words:

• impossibleness