Here are some examples:
* Single-word compound nouns:
* fireplace
* sunbeam
* rainbow
* Two-word compound nouns:
* high school
* dining room
* best friend
* Three-word compound nouns:
* mother-in-law
* long-term relationship
* state-of-the-art technology
* Compound nouns with hyphens:
* well-being
* sister-in-law
* up-to-date
Compound nouns can be written as one word, two words, or with hyphens. The specific form depends on the noun and its usage.