How to spell English compounds

How trustworthy is this result?

The percentage value for the most likely spelling of your compound is based on the word list that I used to discover the CompSpell spelling strategy. The actual result may therefore be slightly lower than the percentage values would suggest – but when I tested this spelling strategy with new compound words, it successfully produced the most likely spelling in 73% to 76% of cases. I also tested two highly educated English native speakers and got a similar result. As a consequence, the result can be considered relatively trustworthy.

Exception principles

Even so, my strategy may sometimes suggest a spelling that contradicts your intuition. For instance, you may feel that the suggested spelling of dish washer with a space is not as good as hyphenated dish-washer. In such a case, it may be that some quality of your compound is more important than the general rule. The following exception principles can help you check whether this is the case:

Spelling with a space is often preferred for NOUN compounds if

  • most other compounds ending with the same second part use a space
  • the first part is an adjective (main course)
  • the compound is stressed on the second part (black PEPPER)
  • the second part of the compound can be used as a cover term for the compound (a pot plant is a kind of plant)
  • the compound seems to be of foreign origin (anabolic steroid).

NOTE: Adjectives, adverbs and verbs are usually not spelled with a space.

Spelling with a hyphen is often preferred if

  • most other compounds beginning with the same first part or ending with the same second part are hyphenated
  • the compound ends in -ing (thought-provoking), -ed (house-trained) or -er (dish-washer)
  • the second part of the compound cannot be used as a cover term for the compound (a grown-up is not a kind of up)
  • there are vowels at the end of the first and the beginning of the second part (eyeopener)
  • one of the parts is a grammatical word (far-off)
  • the first part is a verb (glow-worm)
  • the second part is no noun (top-heavy, spoon-feed)
  • the parts are exactly identical (fifty-fifty)
  • the parts are very different, e.g. regarding their length (six-shooter) or how common they are (well-nigh)

Spelling as a single word is often preferred if

  • the first part is stressed
  • the second part is a general word like man (weatherman).

Since dish-washer ends in -er, this is a good argument in favour of spelling it with a hyphen rather than with a space.

If you are interested in more details (like the full list of exception principles), just take a look at my book English Compounds and their Spelling.