Astronomy, is the distance of the centre of the orbit of a planet from the centre of the sun; that is, the distance between the centre of the ellipse and the focus thereof.

Exception, something reserved, or set aside, and not included in a rule.

It is become proverbial, that there is no rule without an exception; intimating, that it is impossible to comprehend all the particular cases, under one and the same maxim. But it is dangerous following the exception preferably to the rule.