Or the action of becoming a hermit (being alone) but not necessarily on purpose. Some people turn to Hermitism because they have moved to a place far away from their friends. They normally pack up all their possessions and move out to the forest.
Also refers to someone who is forced to stay at their private place of residence on a weekend to avoid being on a club dance floor while sober or due to lack of funds/ lack of confidence/ lack clothes which fit correctly/ generally being lame. These people are also following the principles of Hermitism.