1.
various, all sorts of
Colloquial form of いろいろな. Used to describe many different kinds.
色んな is a colloquial contraction of いろいろな (various). Extremely common in spoken Japanese.
Formality levels
- いろいろな: standard/formal (writing, polite speech)
- 色んな: casual/colloquial (conversation, informal writing)
- いろんな: same word without kanji (also common)
Common patterns
色んな is a pre-noun modifier only. It always precedes a noun and cannot be used as a predicate. Use いろいろだ for the predicative form.