Frombear +‎-proof.

bearproof (comparativemorebearproof,superlativemostbearproof)

1. Resistant tobears.
   • 2006, Dina Fayer, Bob Fayer,Pocket Dad: Everyday Wisdom, Practical Tips, and Fatherly Advice, page100:

     Remember: Bears are smarter than you think! Without abearproof box, it's wise to hang your food from a tree.

bearproof (third-person singular simple presentbearproofs,present participlebearproofing,simple past and past participlebearproofed)

1. (transitive) To make resistant to bears.
   • 2000, Michael Hodgson,Camping for Dummies:

     The first step to take to avoid unpleasant encounters is tobearproof your camp.