Substitute teacher is an adjective and a noun, where substitute is an adjective as defined in the dictionary. However, what about replacement teacher? Replacement is defined as a noun in the dictionary. Does that make replacement teacher a compound noun or is replacement in this situation an adjective nevertheless?

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    It doesn't make any difference. Call it whatever you like. Knowing the name tells you nothing unless you know all about what the names actually mean. And in this case there is no real difference in English. Commented Jan 19, 2014 at 3:29
  • Nouns can act as adjectives in this kind of construction in English. They're called noun adjuncts when they do. The distinction between a noun modified by an adjective or noun adjunct and a simple compound noun is blurry at best. Commented Jan 19, 2014 at 3:35
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    Doesn't the stress pattern change in English between compound nouns and adjective-noun combinations? (Consider the difference in pronunciation between White House and white house.) I believe I pronounce substitute teacher as a compound noun, but replacement teacher as an modifier-noun combination, but it's hard to tell with phrases as multisyllabic as these. Commented Jan 19, 2014 at 4:06
  • A noun can function as an adjective. That's a widely used facility in English. Please also visit English Language Learners and see the questions-answers there.
    – Kris
    Commented Jan 19, 2014 at 8:38

1 Answer 1


Substitute is indeed a noun:

substitute n.: One that takes the place of another; a replacement.

As @EdwinAshworth points out, it is also an adjective:

being such in appearance only and made with or manufactured from usually cheaper materials; synonym: artificial - MW

Regardless of the label, it functions as an adjective in the pair substitute teacher.

Replacement is a noun, and means substitute as well. This is a case of a noun acting as an adjective. Replacement teacher is exactly the same as substitute teacher. Does it retain its essential property as a noun when used as an adjective?

According to Grammar Monster, most compound nouns are made up of two nouns or an adjective and a noun. For example:

Noun + Noun: Bath tub, witchcraft, seaman, wall-paper
Adjective + Noun: Hardware, highway, full moon, whiteboard

Other sites define it similarly, or restrict it to two nouns. Edufind Is even looser, stating it's a noun plus another word and gives examples:

noun + noun: bedroom
noun + verb: rainfall, haircut
noun + adverb: hanger-on, passer-by
verb + noun: washing machine, driving licence
verb + adverb: lookout, drawback
adjective + noun: greenhouse, software
adjective + verb: dry-cleaning, public speaking
adverb + noun: onlooker, bystander
adverb + verb: output, upturn, input

But this we do know: technically, Adj. + Noun => compound noun. And, noun + noun => compound noun. So, I think that is what the comments above are about. Labels may complicate things. There are lots of labels for the same thing. You do not need to know all the labels to learn, write, and speak English.

A substitute teacher is the same as a replacement teacher. Until the replacement becomes permanent. In this economy, both are a blessing.

Edited to reflect information in comment.

  • Hi, medica. I've just come across this thread via another. M-W also gives substitute as an adjective: substitute adjective 1 being such in appearance only and made with or manufactured from usually cheaper materials <substitute wools. That a noun may also be used attributively is accepted by almost all authorities (eg football manager, peanut butter). The picture gets really messy when one tries to classify all premodifiers as being one or the other. An article has been written analysing steel in 'steel bridge'. Commented Aug 8, 2015 at 16:17
  • @EdwinAshworth - Thanks for pointing that out. I'll amend my answer to reflect this. Not an excuse, but sometimes my earlier answers surprise me. :) Commented Aug 8, 2015 at 17:26
  • @Mari-LouA - It's my Achilles' heel of spelling. :) Thanks. Commented Aug 8, 2015 at 18:18
  • Come back!! We need more ladies on EL&U :)
    – Mari-Lou A
    Commented Aug 8, 2015 at 18:53
  • Sorry, I've not made it clear enough. Many would say that 'In the string football boots , football is functioning as a noun (pre-modification of head nouns being one of the properties nouns can display). For the best treatment I can find on ELU, see the discussion, and especially Neil Coffey's answer, to Is this noun used as an adjective? Commented Aug 8, 2015 at 20:49

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