intransitive verb
Definition: To join together with others for a common purpose or to support each other, often in a political or military context.
Example: Several tribes allied to fend off the invaders.
noun
Definition: A person, group, or country that helps or supports another in a common cause or goal, often through a formal agreement or partnership.
Example: The two countries became allies in their fight against terrorism.
transitive verb
Definition: To join or connect with someone or something in a supportive or friendly way, often for a common purpose or goal.
Example: The two countries decided to ally in order to strengthen their defenses against external threats.