There are various ways to express the idea of "following up" with someone or something. Some possible synonyms for "follow up" include "check in," "chase up," "pursue," "keep tabs on," "monitor," "attend to," "update," "revisit," and "touch base." These words can be used in a professional or personal context, and convey a sense of diligence, perseverance, and responsibility. For example, you might check in with a client to see if they received your proposal, pursue a job application by contacting the hiring manager, or touch base with a friend to see how they are doing. Choosing the right synonym can help you communicate your message effectively and enhance your vocabulary.