American English
/wən/
One syllable.
the number 1; a single person or thing, not two or more
“One” is usually pronounced /wən/. In very natural speech, the vowel can disappear, so it may sound like /wn̩/ (“wn”).
the number 1; a single person or thing, not two or more
I have one brother.
She bought one ticket.
Use one when you want to show the exact number. A or an can have a similar meaning, but it is less strong.
one hundred · one thousand · one million · one o'clock
one + singular noun
one + number
a person or thing already mentioned or clear from the situation, used instead of repeating a singular noun
I like the blue one.
This one is cheaper.
In Spanish, this often becomes el or la rather than uno or una.
the right one · the wrong one
the + adjective + one
this/that + one
a single member of a group or set
She is one of my friends.
This is one of the best restaurants.
After one of, the next noun must be plural.
one of the best · one of my friends
one of the + plural noun
one of my/your + plural noun
used before a noun to refer to a particular person, time, or thing without naming it exactly
One morning, he found a wallet.
One person called the police.
one day · one morning · one evening · one night
separately and in order, with only one person or thing at a time
The guests arrived one by one.
only one person or thing each time
Please enter one at a time.
each other
The teammates helped one another.
The form ones is used when this word replaces a plural noun. It is not used for the number 1.