Using the hyphen in temporary compounds before a noun

The hyphen is also used in temporary compounds before a noun, for example a well-written paper. Generally speaking, such temporary compounds are hyphenated before, but not after a noun, for example:

Examples

a well-written paper
The paper was well written.

a long-term problem
The problem was long term.

A full-time position
The position was full time.

Do not use a hyphen

After words ending in -ly

previously published material
a purely theoretical approach
a widely held belief

In Latin or Greek words

an ad hoc explanation
in vitro fertilization

Removing ambiguity

A hyphen can also be used in temporary compounds to avoid ambiguity, for example:

ten year-old children
ten-year-old children