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.
いよいよ本番(ほんばん)だ。
This is finally the real thing.
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.

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.