What is the translation of 熱鬧? I came across this word 熱鬧 (In this case, it means very crowded, noisy, lively) in an exercise and it tells me to change it into English. But I can't really find a suitable and precise word to describe this (the three meanings combined).

Example sentence: 這個熱鬧、繁華的城市背後，是一大群生活在貧窮線之下的人。
According to 21 Century renao is an English word borrowed from the Chinese 熱鬧:


  n. “热闹”；(文娱、体育、业余爱好等)热闹有趣的活动 [借用汉语拼音 rènào(热闹)] 


so that should fit exactly what you're looking for but....

If that's not satisfactory enough consider:


lively
bustling
busy
thrilling
exciting (excitement)
noisy