"Form of Misty"
The name Mystie is commonly a female name from the "English" origin.
Mystie is a respelling of Misty, a given name taken from the English word "misty", which describes air that is full of mist or haze. The -ie ending replaces the -y of Misty, a substitution also found in pairs such as Cyndie and Cindy. The spelling Mystie appears in US birth records from 1965 onward.
Misty means "Covered With Mist, Dew".
The pronunciation of Mystie is MIS-tee.