ally · noun C /ˈæ.lɑɪ/
ally (PERSON)
C1 someone who supports you, especially when other people are against you
Dictionary example:
He is generally considered to be the Prime Minister's closest political ally.
Learner example:
The participants are under pressure and they have to find allies and make decisions. (Certificate in Advanced English; C1; Spanish)
ally (COUNTRY)
C2 a country that has agreed to help another country, especially in a war
Dictionary example:
During World War One, Turkey and Germany were allies.
Learner example:
So the allies didn't exclude the Germanies from the world community, including organizations like NATO, the Warsaw Pact or the UN. (Certificate of Proficiency in English; C2; German)