The Word is:”first”

first

/fəːst/
number
adjective: first

1.coming before all others in time or order; earliest; 1st.
“his first wife”
synonyms: earliest, initial, opening, introductory, original More
antonyms: last, closing, developed
never previously done or occurring.
“her first day at school”
coming or encountered next after a specified or implied time, event, etc.
“the first house I came to”
before doing something else specified or implied.
“Do you mind if I take a shower first?”
synonyms: before anything else, first and foremost, firstly, in the first place; More
antonyms: last
for the first time.
“she first picked up a guitar out of sheer boredom”
informal
the first occurrence of something notable.
noun: first; plural noun: firsts
“we travelled by air, a first for both of us”
synonyms: novelty, new experience, first experience, first occurrence, unusual event; informala turn-up for the books
“we travelled by air, a first for both of us”
the first in a sequence of a vehicle’s gears.
noun: first
“he stuck the car in first and revved”
BASEBALL
first base.
“he made it all the way home from first”
BRITISH
the first form of a school or college.
a first edition of a book.
“collectors of modern firsts”

2.with a specified part or person in a leading position.

“the car plunged nose first into the river”

3.the most pressing, likely, or suitable.

“his first problem is where to live”

4.MUSIC

performing the highest or chief of two or more parts for the same instrument or voice.
“the first violins”

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