chal·leng·ing 
/ˈtʃælənʤɪŋ/ adjective
/ˈtʃælənʤɪŋ/ adjective [more challenging; most challenging] : difficult in a way that is usually interesting or enjoyable
▪ I find the job challenging and fun. ▪ Teaching is challenging but rewarding work. ▪ It's a challenging book that requires careful reading. ▪ The slope was challenging for even the most experienced climbers.
▪ I find the job challenging and fun. ▪ Teaching is challenging but rewarding work. ▪ It's a challenging book that requires careful reading. ▪ The slope was challenging for even the most experienced climbers.
— chal·leng·ing·ly adverb
