No Hyphen for Closely Associated Word Pairs
The Hyphen
Rulebase Summary
Certain pairs of words have become so closely associated through common usage that they are recognized as compound nouns and do not require hyphens when acting as adjectives before a noun. These include familiar compound terms such as blood vessel disease, chicken pox rash, credit card fraud, high school records, real estate enterprises, safe deposit boxes, and court reporting pursuits. Because the first element is universally understood as part of the compound noun, no hyphen is needed for clarity.
The same principle applies to familiar measurement compounds in testimony, such as blood pressure, oil pressure, and water level. When an adjective precedes a fixed pair or a measurement phrase before a head noun, keep the phrase open (high blood pressure reading, low oil pressure warning, low water level alarm, low pressure warning). Do not chain hyphens through the whole phrase (low-oil-pressure warning, low-water-level alarm). Some reporters hyphenate a strict two-word compound such as low-pressure before warning; that is reporter preference when the meaning is clear either way.
This rule applies only to established multiple-word compound nouns — it does not apply to ordinary adjective-plus-noun combinations like 'low cost' or 'short term,' which are not recognized compound nouns and should be hyphenated when used as compound modifiers before a noun (low-cost option, short-term plan).
Examples
A. I reviewed the high-school records from that period.
A. I reviewed the high school records from that period.
High school is so closely associated that no hyphen is needed before the noun.
Q. Was this related to credit-card fraud?
Q. Was this related to credit card fraud?
Credit card is an established compound that does not require a hyphen.
Q. Did the nurse note a high-blood-pressure reading that morning?
Q. Did the nurse note a high blood pressure reading that morning?
Blood pressure is a fixed compound. High modifies blood pressure, not blood-pressure reading as a chained unit.
A. The gauge in the boiler room triggered a low-water-level alarm overnight.
A. The gauge in the boiler room triggered a low water level alarm overnight.
Water level parallels blood pressure — keep the pair open; do not hyphenate through it.
Q. Did the dash show a low-pressure warning that morning?
Q. Did the dash show a low pressure warning that morning?
Measurement-plus-warning phrases usually stay open. Hyphenating low-pressure is reporter preference, not required.
Transcript Notes
A compound noun does not change its form when used as a direct adjective — if it is two separate words as a noun, it stays two separate words as an adjective (high school → high school senior, NOT high-school senior; real estate → real estate transaction).
If each word modifies the noun independently and makes sense on its own, the words do not form a unit and are not hyphenated. Test: try each word alone in front of the noun — if both work separately, no hyphen is needed.
Words that already represent a recognized unit in the dictionary (income tax, social security, credit card) are not hyphenated even when used as adjectives.
In mechanical and medical testimony, phrases such as low pressure warning and low oil pressure warning are often left open — the same pattern as high blood pressure reading. Do not chain hyphens through oil pressure or water level. Hyphenating low-pressure before warning is a reporter-preference choice, not a flagrant error either way.
Style Guide References (5)
Morson's
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