1. A state, group, or individual formally joined or associated for a common purpose
France and Britain were allies during World War II.
França e Grã-Bretanha foram aliados durante a Segunda Guerra Mundial.
2. A person who cooperates or helps another
She found an ally in her colleague who supported her project.
Ela encontrou uma aliada em sua colega que apoiou seu projeto.
3. (verb) To unite or form an alliance with someone or something
The two companies decided to ally themselves to compete in the market.
As duas empresas decidiram se aliar para competir no mercado.