Emily Dickinson Lexicon

E'QUI-POISE, n. [s as z. L. æquus, equal, and Fr. poids, or rather W. pwys, weight. See Poise.]

Equality of weight or force; hence, equilibrium; a state in which the two ends or sides of a thing are balanced. Hold the scales in equipoise. The mind may be in a state of equipoise, when motives are of equal weight.