Compound Nouns
Compound nouns combine two or more elements into a noun and may be written closed, hyphenated, or open. Their spelling and plural formation are lexical: dictionaries and established usage determine the form rather than a single universal spacing rule.
A compound noun is a noun made from two or more elements. Some are one word, some are hyphenated, and some are written as separate words, so check the established form rather than applying one spacing rule to every compound.
Key details
Important caveats
Scope Boundary
Do not infer that every two-word noun phrase is a compound noun or that all compounds follow one fixed spelling/hyphenation pattern.
Further guidance
Application
Use a reliable dictionary for the established spelling of a particular compound; pluralize according to the structure of that compound rather than automatically changing the last visible word in every case.
Core Rule
Compound nouns can be formed from combinations such as noun + noun, adjective + noun, or verb + noun, and their written form may be closed, hyphenated, or open.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- Nouns: compound nouns — English Grammar Today (opens in a new tab)Cambridge Dictionary · Compound-noun formation, open/hyphenated/closed spellings, plurals and stress patterns