What is the meaning of Threshold?

The lowermost part of a doorway that one crosses to enter; a sill.

An entrance; the door or gate of a house.

Any end or boundary.

The outset of something; the point of entry, or the beginning of an action.

The start of the landing area of a runway.

The quantitative point at which an action is triggered, especially a lower limit.

The wage or salary at which income tax becomes due.

The point where one is mentally or physically vulnerable in response to a provocation or to other nuisances.

Source: wiktionary.org