There are several synonyms for the phrase "divide in half," including "cut in half," "bisect," "split down the middle," and "halve." Each of these phrases refers to the act of dividing something into two equal parts. "Split in two" is another possible synonym, as is "separate into equal halves." These terms may be used in a variety of contexts, from cooking and baking to geometry and mathematics. Regardless of the context, though, they all describe the same basic action: dividing something into two equal parts.