A term, or bound, is one of five traditional dignities Hellenistic astrology assigns a planet within the zodiac, alongside domicile, exaltation, triplicity and decan (or face). Where domicile and exaltation give a planet its strongest standing across a whole sign or a single degree, the term is a narrower, five-way division of each sign, and a planet found within its own term in Gemini is read in this system as holding a minor but real dignity there, weaker than ruling the sign outright but stronger than holding no dignity in that stretch of degrees at all.
The dignity systems were never fully uniform across the Hellenistic and medieval periods, and terms were among the most contested of the five: Ptolemy's Tetrabiblos openly weighs the Egyptian table against a rival, sometimes called Chaldean, before proposing yet a third set of boundaries of his own, a three-way disagreement recorded in the primary sources rather than a modern reconstruction. The Egyptian table, the version this atlas follows for Gemini and the other eleven signs, is the one Vettius Valens transmits in his Anthologies and the version that remained standard in ordinary astrological practice despite Ptolemy's own reservations about it.
Because the five dignities work together rather than in isolation, a planet's term in Gemini is read alongside whatever domicile, exaltation, triplicity and decan it also holds at that degree, the combined picture across all five, not the term alone, being what traditional technique treats as the planet's overall standing at that point in the sign.