FEMA defines a breakaway wall as:
A wall that is not part of the structural support of the building and is intended through its design and construction to collapse under specific lateral loading forces, without causing damage to the elevated portion of the building or supporting foundation system. Any walls below the lowest floor in a building in a V Zone should give way under wind and water loads without causing collapse, displacement, or other damage to the elevated portion of the building or the supporting pilings or columns.
Link to definition:
If you are in a V Zone and have breakaway walls on an elevated home you still may need engineered flood vents. Check with your community or flood insurance provider to see you do.