The principal is the party who agrees to perform an obligation. For example, a builder may contract to construct a building. The obligee expects the principal to fulfill a contract
The surety, then, is the party which guarantees that either the principal will perform adequately or the obligee will be compensated for the principal's failure.
Under insurance is not carrying enough insurance to cover your assets in the even of a liability claim or not carrying enough insurance to satisfy your bank / lienholder. Over insurance is carrying...
Not sure if you meant over insured and under insured. Basically there is a provision in homeowners and condo owner policies called a Co-Insurance penatly if you are not insured to 80% of replacement...