one (EN)
numeral, pronoun, noun, adjective, determiner

numeral “one”

one, 1
  1. the number after zero and before two
    She has one cat that follows her everywhere.

pronoun “one”

singular one, plural ones
  1. a single item or individual from a group
    Out of all the puppies, the littlest one stole my heart.
  2. any unspecified person
    One should always try to be kind, for one never knows what someone else is going through.

noun “one”

sg. one, 1, pl. ones, 1s
  1. a symbol used to represent the number one
    After learning to write, the first digit she mastered was the number one.
  2. a banknote with a value of one dollar
    Can you break this twenty? I need a few ones for the vending machine.
  3. the time when the hour hand on a clock points to one
    The meeting is scheduled to start promptly at one in the afternoon.
  4. a humorous story or remark
    John always has a good one to tell at parties, leaving everyone in stitches.
  5. a person known for a particular characteristic
    She's quite the one for baking; her cookies are always a hit at the bake sale.
  6. the perfect person or thing
    I know it. She is the one for me.

adjective “one”

one, non-gradable
  1. specific or particular when referring to time
    One morning, she woke up to find the garden covered in a blanket of snow.
  2. indefinite or unspecified single item or entity
    In a city, one shop is just like the other.
  3. the only one; without any others
    In the vast expanse of the desert, he was the one source of knowledge for miles around.
  4. entire or undivided
    The team worked as one to achieve their goal.
  5. in harmony or agreement
    After the meeting, the committee was one in their decision to proceed with the project.
  6. identical or the same in nature
    Though they may appear diverse, all these theories are one in their basic principles.

determiner “one”

one
  1. used to give emphasis
    That was one incredible performance you gave on stage!