When it comes to the phrase "gather up," there are a variety of synonyms that can be used to convey a similar meaning. For instance, one might use the word "collect," which refers to the act of assembling items or people together in one place. Alternatively, "assemble" can be used, which implies bringing scattered things together and arranging them in a particular order. Another similar term is "round up," which suggests the act of gathering up people or animals in a specific location or space. Additionally, "amass" can be used to suggest the gathering or accumulation of a large quantity of something over time.