The word "threshold" refers to a point or level at which something begins or changes. It can be understood in both physical and metaphorical senses. Physically, it can mean the entrance of a room (like a doorframe), while metaphorically, it can refer to the beginning of a new stage or experience in life, such as reaching a threshold of knowledge or experience.
The word "threshold" originates from the Old English term "þrescold," which is derived from "þresh" (to thresh, or separate grain from chaff) and "hold" (a place or a space). The combination suggests the idea of a boundary or entry point, especially at the entrance of a place.