ally: Meaning and Definition of

al•ly

1. 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.

1. to enter into an alliance; join; unite.

1. 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.
2. 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.
3. a person who associates or cooperates with another; supporter.

-ally

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