The Word is:”in”

in

/ɪn/

preposition

1.expressing the situation of something that is or appears to be enclosed or surrounded by something else.
“I’m living in London”
synonyms: inside, within, in the middle of, within the bounds/confines of; More
2.expressing a period of time during which an event happens or a situation remains the case.
“they met in 1885”
synonyms: during, in the course of, in the time of, over
“they met in 1921”

adverb

1.expressing movement with the result that someone or something becomes enclosed or surrounded by something else.
“come in”
synonyms: inside, indoors, into the interior, into the room/house/building, within
“his mum walked in”
2.expressing the situation of being enclosed or surrounded by something.
“we were locked in”

adjective

1.present at one’s home or office.
“we knocked at the door but there was no one in”
synonyms: present, home, at home; More
2.informal
fashionable.
“pastels and light colours are in this year”
synonyms: fashionable, in fashion, in vogue, voguish, stylish, in style, popular, (bang) up to date, up to the minute, modern, modish, trendsetting, chic; More
nouninformal
1.a position of influence with someone powerful or famous.
“she got an in with the promising new artist”

Source credit: Google