COMPOUND WORDS - ROOT WORDS AS 'PREFIX'

(THE ROOT WORD IS USUALLY THE EMPHASIZED WORD (EVEN THOUGH THE SECONDARY WORD IS THE ONE THAT DISTINGUISHES IT.)

COMPOUND (COMPOSITE) WORDS and TERMS. 
(closed, hyphenated, open)

NOUNS serve almost as PREFIXES for their various uses in longer terms.
the emphasis is usually on that noun (for example “car keys”)  but being a longer phonetic sequence it sounds like a new word, perhaps unrelated to cars, like “cardigan”, but in fact it’s not.  

present this as vocabulary.