The term "first sacker" is often used in baseball to refer to the player who plays the position of first baseman. However, there are several other synonyms for this term that are commonly used. Some of the most common synonyms for "first sacker" include "initial baseman," "initial defender," and "initial fielder." Additionally, some baseball enthusiasts may use more informal terms like "first base guy" or "first base player" to refer to the player who plays this position. Ultimately, regardless of what term is used, the first baseman is a key position player who is responsible for fielding and catching balls that are hit in the vicinity of first base.