"threshold" in the noun sense
1. threshold
the starting point for a new state or experience
"on the threshold of manhood"
2. threshold, limen
the smallest detectable sensation
3. doorway, door, room access, threshold
the entrance (the space in a wall) through which you enter or leave a room or building the space that a door can close
"he stuck his head in the doorway"
4. doorsill, doorstep, threshold
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
5. brink, threshold, verge
a region marking a boundary
Source: WordNet® (An amazing lexical database of English)
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