Passersby (originally, passers-by) is the plural form of the term ‘passerby’ (originally, passer-by). This is one example of a special group of compound noun phrases that appear with internal pluralization, and are sometimes hyphenated with the final word not being the main noun. Besides ‘passersby’, there are other words, which can be categorized into 3 groups: those with the adjective ‘general’ (directors-general, secretaries-general and so on); those with the phrase ‘-in-law’ (fathers-in-law and so on); and miscellaneous (lookers-on, ladies-in-waiting and so on).