The phrase "big boards" refers to large, massive boards that are often used for construction or other heavy-duty activities. There are a variety of synonyms that can be used to describe these types of boards, such as "planks," "panels," "slabs," or "timbers." Each of these words conveys a sense of strength and durability, which is typically associated with big boards. Additionally, other terms that may be used to describe big boards include "sheets," "plates," or "tiles," depending on the specific type of board being used. Overall, there are numerous words that can be used to describe big boards, all of which convey a sense of size, weight, and durability.