Keep sight is a phrase that means to maintain visual contact with someone or something. There are many synonyms for this phrase that can be used to express the same idea in different ways. One synonym is "maintain a visual on," which conveys the same meaning but with a more technical tone. Another option is to use the phrase "keep in view," which puts more emphasis on the idea of keeping something within one's line of sight. Other possible synonyms include "observe," "watch," "monitor," and "keep an eye on." Each of these phrases can be used in different contexts to convey the idea of maintaining visual contact with someone or something.