/ ˈjuːsfəlnəs; NAmE / noun
[ U ] the fact of being useful or possible to use :
There are doubts about the usefulness of these tests.
The building has outlived its usefulness.
/ ˈjuːsfəlnəs; NAmE / noun
[ U ] the fact of being useful or possible to use :
There are doubts about the usefulness of these tests.
The building has outlived its usefulness.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005