The Word is:”one”
one
/wʌn/
number
cardinal number: one; adjective: one; noun: one; adverb: one
1. the lowest cardinal number; half of two; 1.
“there’s only room for one person”
plural noun: ones
“they would straggle home in ones and twos”
synonyms: a single, a solitary, a sole, a lone
“only one person came”
“her one concern is to save her daughter”
synonyms: only, single, solitary, sole
“her one concern was her daughter”
“electronics is one of his hobbies”
determiner: one
“one afternoon in late October”
synonyms: some, any, a certain
“one day they’ll come”
“he worked as a clerk for one Mr Ming”
a noteworthy example of (used for emphasis).
“the actor was one smart-mouthed troublemaker”
“I’ll be there at one”
plural noun: ones
2. the same; identical.
“all types of training meet one common standard”
synonyms: only, single, solitary, sole
“her one concern was her daughter”
3. informal
a joke or story.
“the one about the Englishman, the Irishman, and the Yank”
4. informal
an alcoholic drink.
“a cool one after a day on the water”
5. West Indian
alone.
“the time when you one tackled a field of cane and finished before the others had even started”
pronoun
pronoun: one
1. referring to a person or thing previously mentioned or easily identified.
“her mood changed from one of moroseness to one of joy”
2. a person of a specified kind.
“you’re the one who ruined her life”
a person who is remarkable in some way.
“you never saw such a one for figures”
3. used to refer to the speaker, or any person, as representing people in general.
“one must admire him for his willingness”
Source credit: Google