Definition of "Threshold" :

noun: the sill of a door; a horizontal piece of wood or stone that forms the bottom of a doorway and offers support when passing through a doorway

noun: the entrance (the space in a wall) through which you enter or leave a room or building; the space that a door can close

noun: the smallest detectable sensation

noun: a region marking a boundary

noun: the starting point for a new state or experience

"On the threshold of manhood."