A five-year-old whiskey A five year old boy
Should multiple adjectives describing a noun be hyphenated?
Generally, hyphenate two or more words when they come before a noun they modify and act as a single idea. This is called a compound adjective.
Examples:
an off-campus apartment
state-of-the-art design
a five-mile-long road
A five-year-old whiskey (or whisky sometimes)
A five-year-old boy