under one's arm
Ela levava uma grande pasta de couro debaixo do braço.
She was carrying a large leather briefcase under her arm.
Ela tem um livro debaixo do braço.
She has a book under her arm.
Ele carregava um livro debaixo do braço.
He was carrying a book under his arm.
Ela levava a caixa debaixo do braço.
She was carrying the box under her arm.
Tom colocou o termômetro debaixo do braço.
Tom placed the thermometer under his arm.