Which suffix is ​​used to change the word 'short' into verb form?

কিছু noun/adjective এর শেষে '-en' suffix যোগ করে verb গঠন করা হয়।
যেমন:
Short - Shorten
Black - Blacken
Broad - Broaden
Dark - Darken 
Fright - Frighten
Haste - Hasten
Height - Heighten 
Length - Lengthen 
Less - Lessen 
Sharp - Sharpen
Strength - Strengthen
Sweet - Sweeten
Tight - Tighten
Weak - Weaken