Travel.state.gov defines a Limited Validity passport as, “…any passport issued with less than full 10-year validity for those 16 years and older and less than 5-years validity for those under age 16.” Basically it’s a temporary passport issued if yours was lost or stolen while traveling abroad, or you have a citizenship, identity, or name documentation deficiency at the point of application. It will get you out the door, but requires you to provide full documentation before you can get your full passport that’s valid for 10 years (5 years for children under 15).