Compound adjectives most commonly end in an adjective (e.g. homesick), or in an -ing or -ed adjective form (e.g. ground-breaking, short-sighted).
Compound verbs are far less common than compound nouns or adjectives. They can be made by making a verb from another word class, normally from an already existing compound noun (e.g. a daydream – to daydream).
Writing compound words
Sometimes compound words are written separately (nail polish), sometimes with a hyphen (short-sighted) and sometimes as one word (eyelashes). Often new compounds are written as two separate words and, as they become more familiar, they are either connected with a hyphen (-) or made into one word.
There are some general rules and guidelines for when to use hyphens:
when there is a prefix (e.g. post-war, pre-lunch, self-interest, semi-skilled)
when a compound adjective comes before a head noun (e.g. awell-knownsinger, anangry-soundingemail)
when the pre-head item in a compound is a single capital letter (e.g. U-turn, X-ray, D-day)
when words are difficult to recognise as compounds and could be confused
The band has decided to re-form. (form again)
The Government promise to reform the health system. (improve)
when compound adjectives containing numbers appear before a noun
A twenty-two-year-old cyclist won the race.
From here to Tokyo, that’s a twelve-hour flight at least.
If you’re not sure about whether to use a hyphen, a good dictionary will tell you.