[chal.leng.ing] adj (1842) 1: arousing competitive interest, thought, or action "a ~ course of study"
2: invitingly provocative: fascinating "a ~ personality" -- chal.leng.ing.ly adv
[chal.leng.ing] adj (1842) 1: arousing competitive interest, thought, or action "a ~ course of study"
2: invitingly provocative: fascinating "a ~ personality" -- chal.leng.ing.ly adv
Merriam-Webster English vocab. Английский словарь Merriam Webster. 2012