Looking up...
いろいろな意見を聞きました。
I heard various opinions.
Various; different kinds of; a variety of
いろいろな問題があります。
There are various problems.
いろいろな方法を試しました。
I tried various methods.
Used to describe multiple different items or options. Often written as 色々 but pronounced the same.
All sorts of things; many things
いろいろお世話になりました。
Thank you for everything you've done for me.
Used to express gratitude for multiple favors or assistance received.
いろいろ is the standard form, while いろんな is a colloquial contraction often used in speech. Both are interchangeable in most contexts.
いろいろ can precede nouns directly (いろいろな本) or be used with の to modify nouns (いろいろの本).
From いろ (色, 'color') + いろ (色, 'color'), with reduplication to emphasize multiplicity. The word originally referred to colors but evolved to mean 'various' or 'many kinds.'
いろいろ is informal and commonly used in everyday speech. It can be used as a na-adjective, adverb, or noun depending on context. When followed by の, it functions as a noun (e.g., いろいろの問題).