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Plurals and Possessives


Form plurals of nouns or family names that end in s, z, x, ch, and sh by adding es. Example: The Joneses live in Gates.

Form plurals and possessives of proper names that end with s, x and z. Examples: Burns’ poems, Marx’s theories, Savitz’s holdings

Plural possessives combine the above rules. Example: the Joneses’ reunion.


Form plurals of the following by adding s alone.


the late 1960s
several YMCAs
CODs and IOUs
MAs and PhDs

For single letters, use ’s.


Mind your p’s and q’s
He learned the three R’s

Latin Plurals

Academia is home to many surviving Latinisms, but it’s easy to confuse singular and plural forms. Most commonly you’ll find (singular/plural):

  • addendum/addenda
  • alumna (female)/alumnae
  • alumnus (male or general)/alumni
  • appendix/appendices
  • appendixes, not appendices
  • datum/data
  • emerita (female)/emeritae
  • emeritus (male or general)/emeriti
  • erratum/errata
  • index/indices
  • memorandum/memoranda
  • millennium/millennia
  • symposium/symposia

Last Updated 2/22/11