ally

UK: noun: /ˈælaɪ/, verb: /əˈlaɪ/

US: /n. ˈælaɪ, əˈlaɪ; v. əˈlaɪ/

US: (v. ə lī′; n. al′ī, ə lī′)

Inflections of 'ally' (n): npl: allies

Inflections of 'ally' (v): (⇒ conjugate)

allies

v 3rd person singular

allying

v pres p

allied

v past

allied

v past p

WordReference Random House Learner's Dictionary of American English © 2025

al•ly /n. ˈælaɪ, əˈlaɪ; v. əˈlaɪ/   n., pl. -lies, v., -lied, -ly•ing. 
n. [countable]

1. Government a nation, group, or person associated with another or others for some common cause or purpose.See Allies.

v. 

2. Government to unite formally, such as by treaty, league, or marriage;
   enter into an alliance: [~ + oneself + to/with + object]
   Russia allied itself with France.
   [no object]
   They allied against the common enemy.
3. to associate or connect by some mutual relationship:
   [~ + oneself + to/with + object] They allied themselves with the stockholders to gain control of the company.

-ally, suffix. 

1. -ally is used to form adverbs from certain adjectives ending in -ic: terrific (adj.) +
   -ally → terrifically (adv.).

WordReference Random House Unabridged Dictionary of American English © 2025

al•ly  (v. ə lī′;n. al′ī, ə lī′), v., -lied, -ly•ing, n., pl. -lies. 
v.t. 

1. Government to unite formally, as by treaty, league, marriage, or the like (usually fol. by with or to):
   Russia allied itself to France.
2. to associate or connect by some mutual relationship, as resemblance or friendship.

v.i. 

3. Government to enter into an alliance;
   join;
   unite.

n. 

4. Government a person, group, or nation that is associated with another or others for some common cause or purpose:
   Canada and the United States were allies in World War II.
5. Biology a plant, animal, or other organism bearing an evolutionary relationship to another, often as a member of the same family:
   The squash is an ally of the watermelon.
6. a person who associates or cooperates with another;
   supporter.

• Latin alligāre to bind to. See alloy
• Anglo-French al(l)ier, aillaier, Old French alier
• Middle English alien 1250–1300

al•li′a•ble, adj. 
Synonyms

• 1. unify, join, combine, wed.
• 4. partner, confederate.
• 6. friend, aide, accomplice, accessory, assistant, abettor; colleague, coadjutor, auxiliary, helper.

Antonyms

• 4, 6. enemy, foe, adversary.

-ally, 

1. an adverbial suffix attached to certain adjectives with stems in -ic that have no forms ending in -ical: terrifically.

• -al¹ + -ly

Collins Concise English Dictionary © HarperCollins Publishers::

ally verb / əˈlaɪ/ ( -lies, -lying, -lied)
usually followed by to or with:

1. to unite or be united, esp formally, as by treaty, confederation, or marriage
2. (tr; usually passive) to connect or be related, as through being similar or compatible

noun / ˈælaɪ əˈlaɪ/ ( -lies)

1. a country, person, or group allied with another
2. a person or group that supports another, esp in the face of opposition
3. a plant, animal, substance, etc, closely related to another in characteristics or form

Etymology: 14th Century: from Old French alier to join, from Latin alligāre to bind to, from ligāre to bind

ˈallyˌship noun