Many words are compound and hyphenated in English:
one-on-one
long-term
self-esteem
well-being
six-pack
all-inclusive
four-legged
father-in-law
off-road
post-traumatic
cross-country
high-quality
Some of these words lose their hyphen after a while:
e-mail 〰 email
note-book 〰 notebook
data-base 〰 database
multi-task 〰 multitask
mega-byte 〰 megabyte
Numbers between twenty-one and ninety-nine are spelled with a hyphen:
twenty-nine
fifty-five
eighty-six
Two-word simple fractions are also spelled with a hyphen.
Example:
She has finished two-thirds of the book.
