bilaterally symmetrical adj 1: capable of division into symmetrical halves by only one longitudinal plane passing through the axis [syn: {zygomorphic}, {bilaterally symmetrical}, {zygomorphous}] [ant: {actinomorphic}, {actinomorphous}] 2: having identical parts on each side of an axis [syn: {bilateral}, {isobilateral}, {bilaterally symmetrical}, {bilaterally symmetric}]