I would like to ask you a question on how to use a noun in the role of an adjective in front of another noun. The point at issue here is the number of the first noun. Let me give you an idea what I have on my mind. I have many a time come across the phrase "profit percentage" on one hand, and "profits percentage" on the other. Is there any significant difference between these two expressions? If so, what is it?
A more general question arises. When should I put a noun in the singular and when in plural before another noun? Is there any strict rule or is it just common sense?
I hope the matter I am trying to put forward is clear enough and you understand what my point is. Thank you for any advice, Professor.
Best regards, Dariusz
The easiest way to answer this question is to think of as many noun + noun compound nouns as possible, and then examine the list for a generalisation. Holiday resort, air line, post office, bull terrier, apple pie, stick insect, butterfly, flower pot, stamp collection, car dealer - no plurals there. In fact, the only example that springs to mind is where workers with a collection of different occupations (trades) within the same industry joined together to form a trades union. If the workers all carried out the same job, it would be a trade union. In Britain there is an organisation that brings together all societies of this type, known as the Trades Union Congress, but note that the word union is not pluralised despite the fact that logically it could be, as it is a congress (i.e. a coming together) of different trade unions and trades unions! It may be of significance also that most people talk, incorrectly, about the Trade Union Congress. This may partly be because it is easier to say. A similar explanation may lie behind the compound noun referring to a skilled workman such as a plumber or builder, a tradesman. Despite the person having only one trade (carpenter, electrician, etc.) the s is always present in this word.
Usually we combine nouns in the singular (tree surgeon, animal hospital) with the first noun pluralised only if an important distinction needs making. The Union of Printers and Lithographic Workers covers more than one trade so is a trades union; unlike the National Union of Teachers which represents only one and is therefore a trade union. Therefore your suggestion, Darek, that we just use our common sense is dangerous in this instance, as common sense tells me that a tree surgeon has to deal with more than one tree and an animal hospital treats more than one animal! Common sense might therefore lead me to pluralise these, incorrectly.
Why should pluralised first words of compound nouns be so uncommon? A clue can be found in your original question: ".on how to use a noun in the role of an adjective.". In English, unlike in most European languages, we do not pluralise adjectives, so this is why a noun used as an adjective is not usually pluralised. However, we must always bear in mind that language is made by ordinary people, not theoreticians, hence tradesman simply because it is easier to say than trade man!
An interesting example concerns army personnel. Because England was invaded and ruled by the Norman French from 1066, words to do with the army are nearly all from French, not Anglo-Saxon (soldier, fort, colonel, brave, victory, etc.). But French places an adjective after the noun, unlike in English. Since many words in English can be used either as nouns or adjectives, this can lead to confusion.
Take two military ranks, major general and sergeant major. In each of these compounds, which word is the noun and which the adjective? Hint - is a major general a kind of major, or a kind of general? Clearly he is an important general, so general is the noun and major the adjective - we can have two major generals. But what about my second example? Is a sergeant major a kind of major or a type of sergeant? Here the French word order is used, so he is an important sergeant. I remember my English teacher at school many years ago telling us that two of these warrant officers were therefore two sergeants major, as it was the noun that should be pluralised. However, I think he was wrong - we treat a compound noun as one unit i.e. one noun, and therefore make the plural by adding s to the end i.e. two sergeant majors. But note that this is an argument between a now dead English teacher, and your old professor. Ordinary people would just add s to the second word without thinking, or analysing the underlying grammar - and they are right!
As I have written here many times before, grammar is descriptive not prescriptive. My job is to say what native speakers do, not to attempt to impose rules, strict or otherwise. Therefore, Darek, use the first word of compounds in the singular and you will be right 99.99 per cent of the time.