RULES FOR THE FORMATION OF COMPOUNDS
I Two nouns used together as a name form a compound noun unless:
(a) The first is used in a descriptive or attributive sense, that is, is really an adjective, or
(b) The two are in apposition.
Various uses of the noun as an adjective, that is, in some qualifying or attributive sense are when the noun conveys the sense of:
1. “Made of;” leather belt, steel furniture.
2. “Having the shape, character, or quality of;” diamond pane, iron ration, bull calf.
3. “Pertaining to, suitable for, representing;” office desk, labor union.
4. “Characterized by;” motor drive.
5. “Situated in, and the like;” ocean current, city life.
6. “Supporting or advocating;” union man, Bryan voter.
7. “Existing in or coming from;” Yellowstone geyser, California lemon.
8. “Originated or made by, named for;” Gordon Press, Harvard College.
Placing the two nouns in apposition is much the same as using the first as an adjective.
Such compounds are generally written as two words without the hyphen, but see specific rules for use of hyphens.
II Every name apparently composed of a plain noun and a noun of agent or verbal noun, but really conveying the sense of a phrase with suffix er, or, or ing, should be treated as a compound; roller distribution.
III Possessive phrases used as specific names (generally plants) are treated as compounds.
They are hyphenated unless very common, in which case they are closed up; crane’s-bill, ratsbane.
IV Any phrase used as a specific name in an arbitrary application not strictly figurative is written as a compound; blueberry, red-coat, forget-me-not.
V Any pair of words used as one name of which the second is a noun but the first not really an adjective should be written as a compound; foster-brother, down-town, after-consideration.
As elsewhere the use of the hyphen depends largely in the familiarity of the phrase; spoilsport, pickpocket.
VI Any two words other than nouns should be treated as a compound, generally solid, when arbitrarily associated as a name; standpoint, outlook.
VII A name or an adjective made by adding a suffix to a proper name compounded of two words should be treated as a compound with a hyphen; East-Indian, New-Yorker. If the name is not inflected this rule does not apply; East India Company, New York man.
VIII Any pair or series of words arbitrarily associated in a joint sense different from their sense when used separately, should be compounded; workman-like, warlike.