n. In astronomy, the conjunction or opposition of a planet with the sun, or of any two of the heavenly bodies. On the phenomena and circumstances of the syzygies depends a great part of the lunar theory.n. In ancient prosody, a group or combination of two feet.n. In algebra, a linear function in the variables. See syzygetic.n. In zoology, the conjunction of two organs or organisms by close adhesion and partial concrescence, without loss of their identity; also, the thing so formed, or the resulting conformation; a syzygium: a term variously applied.