The phrase "bottom on" can have several synonyms depending on the context it is being used. For example, it can mean "resting on," "sitting on," "supported by," "leaning against," or "lying upon." In the case of clothing, "bottom on" often refers to pants or shorts, and synonyms can include "wearing," "dressing in," or "putting on." Additionally, in a figurative sense, "bottom on" can imply a hierarchical structure or position, synonymous with "lowest rank," "least senior," or "inferior." In sum, while the phrase "bottom on" may have a few direct synonyms, it's essential to consider the context of the phrase to choose the best one.