The word "Terms" (also known as "Bounds") comes from the Latin word "termini". Every sign is divided into 5 inequal sections called terms (or bounds), each term being ruled by one of the traditional "non-light" planets i.e Mercury, Venus, Mars, Jupiter and Saturn.

The section of a sign - the "Terms" in other words - that a planet in that sign is also in, determines which of the above planets is its "Terms ruler". There are three systems of Terms: the Egyptian, the Chaldean and a very ancient one Ptolemy discovered, and thus it is called the Ptolemaic system. They have different ways of dividing up the degrees of each sign into Terms. AstroGold has wheel styles for the Egyptian and the Ptolemaic systems.

The Terms ruler has an influence over planets in it, and a planet in its own Terms is strengthened, while a planet in the Terms of another is colored by (acts "in terms of") that planet. So for example within the sign it's in Venus in its own Terms is enhanced but in the terms of Saturn in that sign has it's normal benefit reduced, and in the Terms of Mars has less power to manifest it's normal benefit. Saturn in the Terms of Venus would be softened, not so harsh and less likely to manifest malevolence.