The crossword solution for the term ENCYCLOPEDIA BK is VOL, which stands for volume. Volume is a unit of measurement used to quantify the size of an object or the amount of space it occupies. It is typically measured in liters, cubic meters, or cubic feet. Volume is also used to measure the capacity of a container, such as a bottle or a box. In the context of an encyclopedia, volume refers to the number of books that make up the entire set.