Another term for a portable ladder is a __________ ladder.

A portable ladder is commonly referred to as a ground ladder. This term highlights its use and functionality, as these ladders are designed to be placed on the ground to access elevated areas during firefighting operations. Ground ladders are versatile and can be easily transported to the scene of an emergency, allowing firefighters to reach windows, rooftops, or other heights quickly and safely.

While "straight" and "single" ladders can describe specific types of portable ladders (as straight ladders are often single-section ladders), the term "ground ladder" encompasses a broader category of portable ladders, making it the most accurate answer in this context. "Bangor" ladders refer specifically to a type of extension ladder, which may not be classified simply as portable like ground ladders.