Keller's Learn to Read Latin says

                 Derivatives                          Cognates
pars         parcel; parse; part                   pair; par; compare

I was wondering why some English words are considered as derivatives of Latin pars, while others as cognates?

I found that for example, https://www.etymonline.com/word/pair, pair in English is derived from par in Latin. In Latin, par is an adj. version of noun pars. So is there no derivative relationship between par and pars in Latin, so that we may consider pairs in English as a derivative of pars in Latin, or parcel as a derivative of par in Latin?


1 Answer 1


For two words to be cognate, they need to share an ancestor at some point. This is a much broader category than one being derived from the other.

To use a biological metaphor, your siblings are related to you, and share an ancestor with you, but they are not descended from you. Instead, you are both descended from your parents.

  • Thanks. Which Latin word has all the words listed in the post as derivatives? How are par and pars related within Latin?
    – Tim
    Jun 7, 2023 at 5:07
  • 1
    @Tim No Latin word has all of those as derivatives. Their common ancestor lies prior to Latin.
    – Draconis
    Jun 7, 2023 at 5:12

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