noun
[ usually sing. ] ( BrE ) a big change or improvement in sth :
His speech called for a step change in attitudes to the environment in the 21st century.
noun
[ usually sing. ] ( BrE ) a big change or improvement in sth :
His speech called for a step change in attitudes to the environment in the 21st century.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005