The state of being related or of referring; what is apprehended as appertaining to a being or quality, by considering it in its bearing upon something else; relative quality or condition; the being such and such with regard or respect to some other thing; connection; as, the relation of experience to knowledge; the relation of master to servant.

It is the bearing (reference, respect, attitude, ordination) of one thing to something else.

an association between things

an intention in the mind, signifying several absolute things

a rather ethereal thing