The term ACORN PROVIDER can be solved by the three letter word OAK. An OAK is a type of tree that is native to many parts of the world, including Europe, Asia, and North America. It is known for its strong wood and acorns, which are a type of nut. Acorns are a food source for many animals, including squirrels, deer, and birds. OAK trees are also an important part of many ecosystems, providing shelter and food for wildlife.