threshold

1. (by extension) An entrance; the door or gate of a house.Examples: "Shy. You that did voide your rume vpon my beard, / And foote me as you ſpurne a ſtranger curre / Ouer your threſhold, […]"broadly

2. (by extension) Any end or boundary.broadly

3. (figurative) The outset of something; the point of entry, or the beginning of an action.Examples: "I arrived at last, did obeisance to my uncle, and told him everything. He thought it over and said: ' […] At the threshold of death, how dare I give you permission to go to England, to cross the seas? But I will not stand in your way. It is your mother's permission which really matters. If she permit you, then godspeed! Tell her I will not interfere. You will go with my blessings.'"; "The first half of this century has been referred to as the golden age of medicine. To me it seems more probable that we are on the threshold of a much greater age."figuratively

4. (aviation) The start of the landing area of a runway.

5. (engineering) The quantitative point at which an action is triggered, especially a lower limit.