if not

conjunction3

1. •
   Indicates that a statement is true in the event that a condition is not satisfied.

   • The plant will die if not watered.
2. •
   Indicates that one statement at least is true, and possibly a second, stronger statement is true; perhaps even.

   • He did as well as expected, if not better.
3. •
   Indicates that one statement is true, but a second is not; but not.

   • I saw that he had improved his manners if not his scruffy appearance.