The Word is:”as”

as

/az,əz/

adverb

adverb: as
1.used in comparisons to refer to the extent or degree of something.

“go as fast as you can”
used to emphasize an amount.
“as many as twenty-two rare species may be at risk”

conjunction

conjunction: as
1.used to indicate that something happens during the time when something else is taking place.

“Frank watched him as he ambled through the crowd”
synonyms: while, just as, even as, at the (same) time that, at the moment that, during the time that, just when; simultaneously
“she caught a glimpse of him as he disappeared”

2.used to indicate by comparison the way that something happens or is done.

“they can do as they wish”
synonyms: in the (same) way that, the (same) way, in the (same) manner that; informallike
“there were some who felt as Frank did”
used to add or interject a comment relating to the statement of a fact.
“as you can see, I didn’t go after all”
synonyms: which, a fact which, something which
“I’m away a lot, as you know”

3.because; since.

“I must stop now as I have to go out”
synonyms: because, since, seeing that, seeing as, considering that, on account of the fact that, in view of the fact that, owing to the fact that; More

4.even though.

“sweet as he is, he doesn’t pay his bills”
synonyms: although, though, even though/if, in spite of the fact that, despite the fact that, notwithstanding the fact that, notwithstanding that, for all that, while, whilst, albeit, however
“try as she did, she couldn’t laugh”

preposition

preposition: as

1.used to refer to the function or character that someone or something has.
“it came as a shock”
synonyms: in the guise of, with the appearance of, in the character of, so as to appear to be More
2.during the time of being (the thing specified).
“he had often been ill as a child”

Source credit: Google