These come under Canon 603 of the new Canon Law. These individuals, men or women, are vowed to follow a fully eremitical way of life when they are approved of and blessed by the Bishop. They are dedicated to complete solitude, asceticism and continual prayer. Fasting, celibacy, poverty, silence and work are an integral part of this radical form of hermit.

http://www.ukvocation.org/a-hermit