IPA: /ˈtʃæl.ɪn.dʒɪŋ/
KK: /ˈtʃælɪndʒɪŋ/
Something that is difficult and requires a lot of effort or skill to deal with or accomplish.
The exam was very challenging, but I studied hard and did my best.
Comparative: more challenging
Superlative: most challenging
Challenging → It is formed from "challenge" (from Old French *chalenge*, meaning to accuse or call to account) and the suffix "-ing" (indicating the action or process). The word "challenging" refers to the action of presenting a difficulty or a call to prove oneself.
Think of a situation where someone is 'calling you to account' ('chalenge') and the '-ing' shows it's happening now. This helps you remember that 'challenging' means something that presents a difficulty or test.