o

   Used as a vocative element in the exalted language of poetry, prayers, and the like, almost as if it were a formal marker of a nonexistent vocative case in English. Impassioned lovers also make use of it: ‘O Romeo, Romeo, wherefore art thou Romeo?’ Used at the beginning of a sentence it is difficult to distinguish this vocative ‘O’ from the exclamatory sound that can express a number of different emotions.

   In earlier literature, however, it sometimes occurs in a tag vocative where its casemarking quality is clearer. ‘Winking away a tear, O Amy,’ says a character in Charlotte M. Young’s The Heir of Redclyffe.

   Vocative ‘O’ is recorded from the thirteenth century, which suggests that it arose naturally, though even then it may have been an importation by learned writers who felt that vocatives needed to be formally distinguished.

   A possible support for the ‘natural’ theory comes in the modern use of suffix ‘-o’, which forms many vocative diminutives, or terms which are more nearly pure vocatives than the words or names which are modified in this way. ‘Boyo’, for example, is used vocatively, whereas ‘boy’ is more frequently used in third person reference, while being available for vocative use. ‘Kiddo’ is a vocative form of ‘kid’, ‘lino’ is a vocative diminutive of ‘line’, itself a short form of ‘linesman’.

   The suffix ‘-o’ can also be added to proper names to form a diminutive, which is then nearly always used vocatively, rather than in third person reference. Anglo-Saxon Attitudes, by Angus Wilson, has a speaker who converts ‘John’ to ‘Johno’ on several occasions. ‘Daddy-o’ is now a standard vocative form, but some would say that it conveniently distinguishes the friendly from the family use of ‘Daddy’. ‘Three-o’ is used as a friendly term of address to a third officer in Doctor at Sea, by Richard Gordon, but the ‘-o’ here may derive from ‘officer’. ‘Dumbo’ and ‘Fatso’ are further examples of vocative conversions which feature final ‘-o’. See also the Wilfrid Sheed quotation under Sage.