the rejection of culturally prescribed goals and the conventional means for attaining them. It could lead to asocialization, depersonalization, social alienation, Anomie (normslessness), psychic dysfunctions, which could on the other hand result in criminal intentions and/or deeds (because of social deviance due to the aforementioned states) or rebellious attitudes (i.e. pursuit of activities advancing new means and new goals, usually via all means possible).
Aside from disrespect and rejection of the institutionalized means and cultural goals (values) of a society, retreatism could also stem from the institutionalization of individualization and most often from social inequalities.
retreat + -ism
see Merton's Strain theory (Sociology) for details
Sources: Dictionary.com, Wikipedia.org