1. Marks the person, place, thing, or basis to which something is related: on or onto; above or over; toward or against as the target of action, speech, thought, attention, or force; resting on, assigned to, or affecting as a state, gift, burden, duty, guilt, or judgment; supported by or based on; or one placed, added, or repeated on or after another. 2. With a stated time or occasion, or a preceding event, at that time or point, or at or after that event: on, at, when, then, or following it.