Final answer:
Malignant tumors are used to describe the largest and most invasive tumors. They can grow beyond the boundaries of the tumor itself, invade neighboring tissues, and spread to other parts of the body through metastasis.
Step-by-step explanation:
The largest and most invasive tumors are described as malignant tumors. Malignant tumors are cancerous and have the ability to grow beyond the boundaries of the tumor itself. They can invade and damage neighboring tissues, and cancer cells from these tumors can break away and spread to other parts of the body through the bloodstream, a process called metastasis.