I would say aggressive, because you can’t really use the other words without being negative.
The character traits that described Jerry in the novel ' Through the Tunnel' are competitive and stubborn.
'Through the Tunnel is a short story written by the British author, Doris Lessing in 1955. The story is about a young boy, Jerry and his mother, who are having their vacation at a beach in a foreign country. Jerry in his stubborn and competitive way set for himself the monumental work of swimming through the river tunnel. He accomplished this successfully and the experience really boost his self confidence.
Hope this helped
The term euphemism refers to polite, indirect expressions which replace words and phrases considered harsh and impolite or which suggest something unpleasant.
Euphemism is an idiomatic expression which loses its literal meanings and refers to something else in order to hide its unpleasantness. For example, “kick the bucket” is a euphemism that describes the death of a person. In addition, many organizations use the term “downsizing” for the distressing act of “firing” its employees.