equa·tion·al \-zhənəl, -zhnəl also -sh-\adjective 1.: of, using, or involving equations 2. a.: dividing into two equal parts — used especially of the mitotic cell division following reduction in meiosis b.: occurring in or resulting from an equational division < equational splits appear early in each chromosome > < each equational half > 3.: having a subject and predicate not linked by a verb < equational sentence > • equa·tion·al·ly\-əl]ē, -əl], ]i\adverb