They are Hyphenated Compound Adjectives.
Each of the phrases in the title of this blog post have compound adjectives (ten-dollar) that describe their nouns (bills).
A hyphen is needed between two words that function together as an adjective before the noun they describe.
Example: The sun-kissed mountains look beautiful this morning.
The words "sun" and "kissed" work together to describe the mountains being lit up by the sun.
Example: My 11-year-old daughter has a birthday coming up.
When an age comes before the person whose age it is, hyphens are needed as seen above because their age is an adjective describing them in some way.
As opposed to: My daughter is almost 12 years old.
In this sentence above, my daughter's age comes at the end of the sentence. Her age isn't being used as an adjective before the subject (daughter) in the sentence, so no hyphens are needed.
Example: She only chews sugar-free gum.
In this sentence, the words "sugar" and "free" work in unison to describe the type of gum she chews.
Here are some other examples:
- Long-term relationship
- Full-time job
- Energy-efficient home
- Cost-effective system
- Family-friendly restaurant
- High-resolution screen
- Industry-specific skills
- Technology-based approach
The most important thing to remember is if the meaning is misleading or confusing in any way without the use of a hyphen, add a hyphen, as seen here:
We are in need of more experienced editors. (This means you need more editors with experience, adding to your existing editing team.)
We are in need of more-experienced editors. (This means that your existing editors don’t have quite enough experience, so you need to hire editors with more experience than the ones you currently have.)
I just read this last passage to my husband to get some feedback, and he had an Aha! moment.
He said he had always wondered about those, referring to compound adjectives.