Meaning of ISM in English

[noun] [C] [informal], esp. humorousAn ism is a set of beliefs.Thatcher is unique among her predecessors in having given the English language a brand new ism, created from her own name. -ist [suffix]-ist is used to form adjectives and nouns which describe (a person with) a particular set of beliefs or way of behaving.Marxist philosophya feminista sexista DaoistCompare -ite.

Cambridge English vocab.      Кембриджский английский словарь.