adverb, interjection
Used to urge action, signal a decisive moment, or express resolve when starting something. Often appears in set phrases like いざという時 (when the time comes) or いざとなれば (if it comes to that).
いざ、出発しよう。
Come on, let's set off.
いざという時のために貯金しておく。
I'm saving money for when the time comes.