House
In plain words
One of twelve slices of your chart, each covering an area of life — money, work, home, and so on. They turn with the horizon, which is why they need your birth time.
In the tradition's terms
The twelvefold division of the local sky, indexed from the ascendant and rotating once a day.
In depth
Signs divide the ecliptic; houses divide the diurnal rotation. They are different circles, and every quarrel about house systems is a quarrel about how to project one onto the other.