Alliance is in its most common use a connection formed by treaty between sovereign states as for mutual aid in war. Partnership is a mercantile word; alliance chiefly political or matrimonial.

J. C. Fernald, English Synonyms and Antonyms (1914)

Example sentences

treaty It seemed clear the Senate would reject the treaty.
coalition The coalition is trying to paper over the cracks.
pact Do Algeria and Tunisia need a mutual defense pact?
confederation Gustavo is the head of the confederation.
relationship What is the relationship between politics and war?
union It is improper to impose sanctions upon the union.

Popularity over time

Word	1850 → 2019	Trend
alliance		steady
treaty		falling
coalition		rising
pact		steady
confederation		steady
relationship		rising

Use in printed books, per decade from 1850 to 2019.

By length

4 letters: team¹, bond¹, axis², pact¹, bund¹
5 letters: party², union²
6 letters: league¹, treaty², fusion², cohort²
8 letters: marriage², relation³, junction², affinity⁴, allyship
9 letters: coalition⁴, alignment³
10 letters: connection³, friendship², federation⁴, consortium⁴, similarity⁵
11 letters: association⁵, combination⁴, partnership³, affiliation⁵, confederacy⁵, concurrence³
12 letters: relationship⁴
13 letters: confederation⁵, copartnership

The small number after each word is its number of syllables (axis² = 2 syllables).

In other languages

Français: alliance
Italiano: alleanza
Español: alianza
Català: aliança