When a planet moves into a new sign of the zodiac or a new house it is said to “ingress” into that place.
For example, when the planet Saturn moves from the zodiacal sign Libra into the sign Scorpio one would say that Saturn is making an “ingress” into Scorpio, or that Saturn has ingressed into Scorpio.
Similarly, if a transiting planet entered into a new house in a native’s chart, an astrologer might say that the planet “made an ingress” into that house.
Ingresses are usually only mentioned within the context of the signs of the zodiac or the twelve houses.
The term is typically used when referring to transits relative to a natal chart, although technically it can be used anytime that a planet enters into a new sign or house.