The basic ally meaning is someone, whether one person, a group or a whole country, that sides with another and helps it, especially against a shared problem or opponent. Two countries that sign a defense treaty are allies; so is the colleague who backs your idea in a tense meeting.
Ally is also a verb. To ally yourself with someone is to join them for a common purpose. In recent decades the noun has gained a social sense too: a person who backs a group that they are not a member of.
Entry at a glance
Meaning
A supporter or partner who is on your sidePart of speech
Noun and verbPronunciation
Noun AL-eye; verb uh-LYE or AL-eyeWord forms
allies (plural), allied (adjective, past tense), alliance (noun)Origin
Old French alier, to unite, from Latin alligare, to bind toOpposite
enemy, foe, rival, opponent, adversaryRegister
Neutral; used in news, history, work and daily talk
Ally meaning and definition, sense by sense
- A country or group joined with another by agreement. "The two nations have been allies for decades."
- Anyone who helps or supports you. "My older cousin was my ally when I told the family I was changing careers."
- A supporter of a group they are not part of. For example, someone who speaks up against unfair treatment of a minority, or a man who backs equal pay for women.
- The verb. To join with others: "The small parties allied to form a coalition."
To define ally in one line: someone on your side. That short ally definition fits each sense above; a longer definition of ally just adds who helps whom and why.
Ally in sentences
- In the debate club, Meera found an unexpected ally in the student she had argued with last term.
- Fresh air and sleep are your best allies during exam season.
- The two companies allied to share the cost of a new research lab.
- He has been a quiet ally to new employees, explaining office rules nobody writes down.
- Rising costs pushed the farmers to ally with local traders.
Grammar: allies, allied and alliance
The plural is allies, never "allys." As a verb, ally usually takes with or to: "ally with a neighbor," "allied to a cause." The adjective allied also means related or connected, as in "medicine and allied health fields." The noun alliance names the partnership itself.
Useful pairings: a close ally, a key ally, a powerful ally, a natural ally, find an ally, an unlikely ally.
How ally entered English
The verb is the older form, recorded in the late 1200s and borrowed from Old French alier, to combine or unite, which goes back to Latin alligare, to bind to. Its earliest English sense was to join in marriage. By the late 1300s it meant to form a partnership. The noun once meant a relative; by the mid-1400s it meant a party joined by treaty. In the First World War, "the Allies" became the name for the nations opposing the Central Powers, and the label returned for the nations opposing Germany, Italy and Japan in the Second World War. The related verb rally, to come together again, shares the same French source.
The social sense of ally
In discussions of equality, an ally is someone outside a group who supports its members' rights or fair treatment, for example by speaking up, listening or using their own influence. This use is common in schools, workplaces and campaigns.
People see it differently. Supporters say the term encourages others to help. Critics, from several directions, say it can become a label people claim without doing much, or that it divides people into groups. Some prefer words like supporter or advocate. Whatever view you hold, the basic meaning is clear: support from outside the group. Related ideas appear on the pages for privilege and diversity.
Close words and the opposite
| Word | Difference |
|---|---|
| Ally | On your side, often for a shared goal or against a shared problem |
| Friend | A personal bond of liking, not necessarily a shared cause |
| Partner | Shares work, risk or a business |
| Supporter | Backs you, often from the sidelines |
| Enemy, foe | The opposite: someone working against you |
Be careful with alley, a narrow lane, which looks similar but is unrelated. The everyday vocabulary hub has many more words like this one.
Frequently asked questions
How would you explain ally to a child?
An ally is someone who is on your side and helps you. It can be a person, a group or a country.
How do you pronounce ally?
The noun is usually AL-eye, stressed on the first part. The verb is often uh-LYE, though many speakers say AL-eye for both.
What is the plural of ally?
Allies. Change the y to i and add es, just like city and cities.
Can a thing be an ally?
Yes, figuratively. You might say "patience is your ally" or "the weather was our ally," meaning it helped you.
Ally or friend: how do they differ?
A friend is someone you like and trust personally. An ally supports you for a shared purpose. A friend can be an ally, but an ally need not be a close friend.
Being an ally to a group: what is involved?
It means supporting people from a group you do not belong to, such as by speaking up against unfair treatment. People debate how the label should be used, but the core idea is outside support.