Hi Adrian, thanks for you answer. I found the meaning in dictionary, buy i don't understand so much. Now it's so clear. I learn programming and the author uses term like this. Thank you very much!!!

'Clunky' means heavy, bulky, and may mean that it makes a noise as it moves. 'Clunkier' means more clunky. 'The larger wagons used now on the trains are clunkier than the ones used before.'