Warning, this verb may not exist. Conjugation is given as example.
Affirmation
Simple form
I will stiffer you will stiffer he will stiffer we will stiffer you will stiffer they will stiffer
V-ing form
I will be stiffering you will be stiffering he will be stiffering we will be stiffering you will be stiffering they will be stiffering
Perfect
I will have stiffered you will have stiffered he will have stiffered we will have stiffered you will have stiffered they will have stiffered
V-ing perfect
I will have been stiffering you will have been stiffering he will have been stiffering we will have been stiffering you will have been stiffering they will have been stiffering
Negation
Simple form
I will not stiffer you will not stiffer he will not stiffer we will not stiffer you will not stiffer they will not stiffer
V-ing form
I will not be stiffering you will not be stiffering he will not be stiffering we will not be stiffering you will not be stiffering they will not be stiffering
Perfect
I will not have stiffered you will not have stiffered he will not have stiffered we will not have stiffered you will not have stiffered they will not have stiffered
V-ing perfect
I will not have been stiffering you will not have been stiffering he will not have been stiffering we will not have been stiffering you will not have been stiffering they will not have been stiffering
Interrogative form
Simple form
will I stiffer? will you stiffer? will he stiffer? will we stiffer? will you stiffer? will they stiffer?
V-ing form
will I be stiffering? will you be stiffering? will he be stiffering? will we be stiffering? will you be stiffering? will they be stiffering?
Perfect
will I have stiffered? will you have stiffered? will he have stiffered? will we have stiffered? will you have stiffered? will they have stiffered?
V-ing perfect
will I have been stiffering? will you have been stiffering? will he have been stiffering? will we have been stiffering? will you have been stiffering? will they have been stiffering?
Interro-negative form
Simple form
will I not stiffer? will you not stiffer? will he not stiffer? will we not stiffer? will you not stiffer? will they not stiffer?
V-ing form
will I not be stiffering? will you not be stiffering? will he not be stiffering? will we not be stiffering? will you not be stiffering? will they not be stiffering?
Perfect
will I not have stiffered? will you not have stiffered? will he not have stiffered? will we not have stiffered? will you not have stiffered? will they not have stiffered?
V-ing perfect
will I not have been stiffering? will you not have been stiffering? will he not have been stiffering? will we not have been stiffering? will you not have been stiffering? will they not have been stiffering?