Number one; first; first place — the top position or the first in order.
彼はクラスで一番だ。
He is number one in the class.
一番を取りたいなら、もっと練習しなさい。
If you want to be first, practice more.
この店が町で一番人気がある。
This shop is the most popular in town.
試合で一番を目指す。
Aim for first place in the match.
As an adverb: the most; best — used to indicate the highest degree in comparisons.
この映画は去年見た中で一番面白かった。
This movie was the most interesting among those I saw last year.
休みの日は家でいるのが一番だ。
On days off, staying at home is the best.
彼女はクラスで一番よく知っている。
She knows it best in the class.
今は一番忙しい時期だ。
This is the busiest time right now.
A game, round, or bout — one match or one round in a series of games.
将棋の一番目は慎重に指した。
I played cautiously in the first game of shogi.
三番勝負の残りの一番は明日行われる。
The remaining one game of the best-of-three will be held tomorrow.
Used adverbially to mean 'as a test', 'for a trial', or 'for the time being' — trying something out tentatively.
新しい方法を一番に試してみよう。
Let's try the new method first as a test.
一番にこのレシピを作ってみたら、思ったより美味しかった。
I tried making this recipe as a test first, and it was better than I expected.
とりあえず一番に連絡してみる。
For now, I'll contact them first to see what happens.
In traditional performing arts (e.g., Noh), 'ichiban' denotes a piece or section — a single song or segment of the program.
能の一番では静かな拍子が用いられることが多い。
In the first piece of a Noh play, a quiet rhythm is often used.
古い楽譜に『一番』と書かれた部分が残っていた。
There remained a part in the old score labeled 'ichiban'.