Compound Words

What is a Compound Word?

A compound word is formed by joining two or more words together to create a new word with its own meaning.

sun + flower = sunflower / tooth + brush = toothbrush

Three Types of Compound Words

Closed Compound Words

Written as one word: toothbrush, bedroom, sunshine, football, notebook, aircraft

Hyphenated Compound Words

Written with a hyphen (-): mother-in-law, well-known, high-tech, self-control, up-to-date

Hyphenated compounds are often used as adjectives before a noun:

• a well-known author (hyphenated)
• The author is well known. (no hyphen after the noun)

Open Compound Words

Written as two separate words: ice cream, living room, post office, high school

Meaning of Compound Words

A compound word's meaning may be:

• Transparent: You can guess it — bookshelf (a shelf for books)
• Opaque: Less obvious — butterfly (not a fly made of butter!)

Tips

• If you're unsure, check a dictionary — compound word style can vary.
• When a compound adjective comes before a noun, hyphenate it.