idiosyncratic

/ˌɪdioʊsɪŋˈkrætɪk/
adjective
  1. Having a strange or unusual habit, way of behaving, or feature that is particular to a person or thing.
    • His idiosyncratic habit of humming while working annoyed his coworkers.
    • The artist's idiosyncratic style uses only shades of blue.
    • Her idiosyncratic way of laughing made everyone smile.