(~s)
1.
The ~ of a building or room is the floor in the doorway, or the doorway itself.
He stopped at the ~ of the bedroom...
N-COUNT: usu sing
2.
A ~ is an amount, level, or limit on a scale. When the ~ is reached, something else happens or changes.
She has a low ~ of boredom and needs the constant stimulation of physical activity...
Fewer than forty per cent voted–the ~ for results to be valid.
N-COUNT: usu with supp, oft N of n, n N
3.
If you are on the ~ of something exciting or new, you are about to experience it.
We are on the ~ of a new era in astronomy.
PHRASE: PHR n/-ing