We're all familiar with how an appositive functions:
My sister, Mary, came to the party. <--I have one sister.
My sister Mary came to the party. <--I have more than one sister.

My question is, in the second instance is "sister" an adjective describing Mary, which the subject of the sentence? Or is "sister" the subject of the sentence and "Mary" is part of a restrictive phrase, such as "My sister [whose name is] Mary came to the party."? Did the "sister" or "Mary" come to the party?

More generally, can relationship nouns be used as adjectives at will?

My husband Robert...
Ali's friend Yula...

etc. where "husband," "friend," etc. are adjectives modifying the proper names.

  • 1
    In all your examples, sister, husband, and friend are nouns. Jun 4, 2021 at 15:56
  • They are nouns as appositives. Without the commas, they are modifiers; with the commas they are supplements (non-restrictive).
    – BillJ
    Jun 4, 2021 at 16:06
  • 1
    For 17 years as a teacher I've thought of appositives as greatly reduced relative clauses (adjective clauses), and have yet to see a counterexample (BUT I'd appreciate seeing one). So in both sentences, "Mary" is an adjective modifying "sister". And yes, the same grammar applies to all relationship words.
    – gotube
    Jul 20, 2021 at 1:39

1 Answer 1


What I was taught in school is that in a construct like this, "My sister Mary came ...", the subject of the sentence is "sister" and "Mary" is a restrictive clause.

As you appear to be aware, this is contrasted with a non-restrive clause, which is set off by commas. Like, "My sister, Mary, came ..."

Though you bring up the example of "My husband Robert came ..." One would think that logically this should be non-restrictive. Presumably you don't have more than one husband that you would need to distinguish which one. (Most women have enough trouble dealing with one husband, never mind two. :-)

It's true that you could substitute an adjective for "My sister" and the sentence could still make sense. Like, "Outspoken Mary came ..." But that doesn't really prove anything. It's often possible to replace a word that is one part of speech with some totally different part of speech and the sentence still makes sense. I could also say "Yesterday Mary came ...". That wouldn't make "yesterday" an adjective.

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