► 副詞
一番 [いちばん] meaning: most rank: 1
☆ 一番安いのはどれですか? ⇨ Which one is the cheapest?
☆ 人生で一番大切なのは健康だ ⇨ Health is the most important thing in life
☆ 私達は一番後ろの列の席に座った ⇨ We sat at the furthest back row seats
一番 [いちばん] [一番最初] meaning: most rank: 1
☆ それを聞いて一番最初に思い浮かんだ事は… ⇨ The very first thing that came to my mind when I heard that is … (☛ 一番最初 is a redundant but commonly used phrase)
一番 [いちばん] [一番最後] meaning: most rank: 1
☆ アルバムの一番最後の曲 ⇨ The very last song of the album (☛ 一番最後 is a redundant but commonly used phrase)
► 名詞
一番 [(2)いちばん] [coll] meaning: best rank: 1
☆ ビールは冷えたのが一番だ ⇨ Beer is best when ice cold
☆ 疲れた時は寝るのが一番だ ⇨ It is best to sleep when you are tired
一番 [(2)いちばん] meaning: first rank: 1
☆ それは明日一番にやろう ⇨ Let’s do it the first thing tomorrow
☆ 彼女は競走で一番になった ⇨ She finished first in the race
一番 [(2)いちばん] meaning: match rank: 4
☆ 優勝の行方を変える重要な一番 ⇨ An important match that changes the course of the championship
More examples:
- 彼は大一番に強い ⇨ He’s clutch in big games
 - 手を洗うのが病気の予防には一番有効だ ⇨ Washing hands is most effective for disease prevention
 - 彼女は今一番人気の有る女優だ ⇨ She is the most popular actress right now
 - やっぱり黒髪が一番綺麗だ ⇨ After all black hair is the most beautiful
 - やっぱり我が家が一番だ ⇨ My home is the No.1 place. There’s no place like home
 - 世界で一番広い国 ⇨ The largest country in the world
 - もしそう出来ればそれが一番良い ⇨ If you can do so, then that is the best
 - ビールは何と言っても冷えているのが一番美味い ⇨ Whatever you say, beer is best when it is cold
 - 私は春が一番好きな季節だ ⇨ Spring is my favorite season
 - 警戒心が薄れた時が一番危ない ⇨ It is most dangerous when cautiousness has been lessened, people have become less cautious
 - 彼の部屋はこの通路の一番奥だ ⇨ His room is at the very end of this hallway
 - 巨人の背番号一番と三番は永久欠番になっている ⇨ The jersey numbers 1 and 3 of the Giants are permanently retired
 - 彼は表彰台の一番上に登った ⇨ He got on top of the podium
 - 彼はこの会社で一番古い人だ ⇨ He’s the person with the longest tenure in this company
 - 南極に一番乗りしたのはアムンセンだ ⇨ Amundsen was first to reach the South Pole