Something which is essential before a subsequent result ensues; a prerequisite: There is a precondition which must be met before Joe's promotion can take place.

1. To subject a person or something, to a special treatment in preparation for a subsequent experience, process, test, etc.: "Henry had to precondition the surface of the table before starting the final painting."
2. Etymology: apparently from Latin precondicere, "to talk over together before, to agree with in advance"; from pre-, "before" + con-, "with, together" + dicere, "to say".