COMPOUND WORDS
What is a compound word?
A compound word is a new word created by joining two (or sometimes more) existing words together.
Examples:
bookcase = book + case
child-friendly = child + friendly
crash landing = crash + landing
smokescreen = smoke + screen
Simple vs More Complex Compounds
Most compounds are made from two free morphemes (words that can stand alone):
book + case
smoke + screen
But sometimes one part is already a complex word:
child-friendly = child + (friend + ly)
crash landing = crash + (land + ing)
Important Difference: Compound vs Affixed Word
Compare these two words:
child-friendly → made of two real words: child + friendly
unfriendly → made of one base word (friend) + two attachments (un- and -ly)
Even though both have three parts, only child-friendly is a true compound because it combines two stand-alone words.
Where do we find compound words?
Compounds are very common in nouns and adjectives, but they can appear in other word classes too.
They are formed in many different combinations:
Noun + Noun → bookcase, crash landing
Adjective + Noun → greenhouse, mobile phone
Noun + Adjective → knee-deep, war-torn
And many other patterns (see the tables in the original text)
How are compound words written?
They can be written in three different ways:
As one solid word: hashtag, crowdfund, bookcase
With a hyphen: off-message, child-friendly, slap-headed
As two separate words: flash mob, crash landing, mother-in-law
Even if they look different on paper, they are still considered one single word (one lexeme) because the parts belong tightly together.
Recent examples (mostly 21st century)
Nouns: flash mob, smart card, hashtag, paywall
Adjectives: crowdfunded, off-message, slap-headed
Verbs: crowdfund, upvote, yarn bomb
Special notes about compound verbs
Compound verbs are less common than compound nouns or adjectives. Examples: kickstart, breastfeed, dryclean, backtrack
Many compound verbs come from:
Conversion (using a noun as a verb): cold-shoulder, mastermind
Back-formation (removing a suffix): babysit (from babysitter), shoplift (from shoplifting)
One more interesting point
The meaning of compound words can be tricky. Sometimes the meaning is clear and transparent (e.g. bookcase = a case for books), but sometimes the relationship between the two parts is less obvious.
In short
Compounding is a very common and productive way in English to create new words by putting two (or more) existing words together — like building with Lego blocks! It works especially well for making nouns and adjectives, and new compounds appear all the time.
