allied; allying
Definition of ally
(Entry 1 of 3)
: to form or enter into an alliance
two factions allying with each other
ally
noun
plural allies
Definition of ally (Entry 2 of 3)
1
: a sovereign or state associated with another by treaty or league
America and its allies
2
: one that is associated with another as a helper : a person or group that provides assistance and support in an ongoing effort, activity, or struggle
a political ally She has proven to be a valuable ally in the fight for better working conditions.
—often now used specifically of a person who is not a member of a marginalized or mistreated group but who expresses or gives support to that group
The storyline on "Glee" captures something larger that we are seeing with a new generation of allies (allies are people who support LGBT rights but aren't LGBT themselves).— David M. Hall
3
: a plant or animal linked to another by genetic or taxonomic proximity
ferns and their allies
-ally
adverb suffixDefinition of -ally (Entry 3 of 3)
: -ly entry 2
terrifically
—in adverbs formed from adjectives in -ic with no alternative form in -ical
Keep scrolling for more
Keep scrolling for more
Keep scrolling for more
Keep scrolling for more
Test Your Vocabulary
Who Knew?
-
- What is a ruelle?

Test your knowledge - and maybe learn something along the way.
TAKE THE QUIZ
Spell words. Make bears.
TAKE THE QUIZLove words? Need even more definitions?
Merriam-Webster unabridged
Words at Play
Ask the Editors
Share ally
Time Traveler for ally
The first known use of ally was in the 14th century
See more words from the same century