Слово "nonchalance". Англо-русский словарь Мюллера

The air of smiling nonchalance with which he approached, proclaimed him still ignorant of the event which had cast its melancholy shadow over the house.

With an air of nonchalance which, under the circumstances, seemed to me to border upon affectation, he lounged up and down the pavement, and gazed vacantly at the ground, the sky, the opposite houses and the line of railings.

Her glance caught Poirot’s and swept over him with the nonchalance of the uninterested aristocrat.

With an air of nonchalance which, under the circumstances, seemed to me to border upon affectation, he lounged up and down the pavement, and gazed vacantly at the ground, the sky, the opposite houses and the line of railings.

He accepted the incident as a sign that her nonchalance was affected.

Vaguely she knew that terrible things were happening there, not from Walter who when she questioned him (for otherwise he rarely spoke to her) answered with a humorous nonchalance which sent a shiver down her spine; but from Waddington and from the amah.