Prior to, before, as in antecedent drainage patterns: the Wind River, Wyoming, for example, probably pre-dates the dome it now cuts through, the river’s erosion keeping pace with the uplift of the dome. Antecedent moisture is the amount of moisture already present in the soil before a specified rainstorm. An antecedent boundary is one drawn before an area is populated, as opposed to a superimposed boundary, fixed by colonial powers.