hyphen
The short mark (-) that joins words or parts of words.
A hyphen joins two or more words that work as a single adjective before a noun: a part-time job, a once-in-a-lifetime trip. It also joins the parts of certain compound words, such as mother-in-law and self-esteem, and the words of a compound number: thirty-six, eighty-one. At the end of a line, a hyphen divides a word between syllables. Each use of the hyphen has its own entry, listed under Hyphen.
Examples
UseShe signed a two-year lease. (The hyphen joins two and year into one adjective before lease.)
UseThe contract runs forty-eight months. (The hyphen joins a compound number.)
AvoidHe took a full time position. (Full and time together describe position, so join them with a hyphen: full-time.)
AvoidIt was a highly-rated restaurant. (An adverb ending in -ly already modifies the next word, so the pair takes no hyphen: highly rated.)