The term "time ball" refers to a device that was used in the past to signal the time to sailors and other seafarers. There are several synonyms for this term, including "time signal ball," "drop ball," and "time gun." The time signal ball was used to indicate the exact time of day, and it was dropped from a high point, such as a lighthouse or tower. The time gun was another method of signaling the time, and it involved firing a cannon or other gun to alert sailors. Whether it was a time signal ball or a time gun, these devices played an important role in helping sailors navigate the seas safely.