いよいよ

いよいよ
adverb
finally; at last; more and more
1. finally; at last; at long last
Indicates that something anticipated is about to happen or has begun.
いよいよ本番(ほんばん)だ。
This is finally the real thing.
いよいよ明日(あした)から新学期(しんがっき)(はじ)まる。
The new semester finally starts tomorrow.
(なが)準備(じゅんび)()て、いよいよ開幕(かいまく)()(むか)えた。
After long preparations, the opening day has finally arrived.
2. more and more; increasingly
Indicates that something is intensifying or becoming more pronounced.
(あめ)がいよいよ(はげ)しくなってきた。
The rain has become increasingly intense.
状況(じょうきょう)はいよいよ深刻(しんこく)になっている。
The situation is becoming more and more serious.
(あき)(ふか)まり、いよいよ(さむ)くなってきた。
Autumn has deepened, and it's getting colder and colder.

TWO MAIN MEANINGS:

1) "Finally/at last" - Used when an anticipated moment arrives

  • いよいよ出発(しゅっぱつ)だ: It's finally departure time

2) "More and more" - Indicates intensification

  • いよいよ深刻(しんこく)になる: to become more and more serious

NUANCE: Often carries a sense of anticipation, excitement, or urgency. Can imply that something important is about to happen after a period of waiting.