1A prerequisite or stipulation in an instrument. 2A future and uncertain event, fact, or circumstance whose existence or occurrence is necessary for the existence or determining the extent of an obligation or liability. See also estate and fee simple. concurrent condition. A condition precedent that must exist, occur, or be performed at the same time as another, but separate, condition before a duty or obligation arises. condition precedent. A condition (other than lapse of time) that must ex...