Synonyms for contingency

Most common

1. Accident — A possibility; something which may or may not happen. A chance occurrence, especially in finance, unexpected…

2. Alternative — the quality of being contingent, of happening by chance

Other

dependence, conjuncture, accidentalness, contingence

n. 1
The quality of being contingent, of happening by chance.
n. 2
A possibility; something which may or may not happen. A chance occurrence, especially in finance, unexpected expenses.

Plural: contingencies → accidents, eventualities, possibilities, contingents…

Contingency or Event?

Since the future is contingent, event comes to have the meaning of a contingency; as, in the event of his death, the policy will at once fall due.

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

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

3 letters: hap¹
5 letters: event²
6 letters: chance¹, hazard²
7 letters: venture²
8 letters: accident³, incident³, casualty⁴, fortuity
9 letters: adventure³
10 letters: occurrence³, contingent³, dependence³
11 letters: alternative⁴, possibility⁵, uncertainty⁴, eventuality⁶, conjuncture, contingence
12 letters: potentiality
14 letters: accidentalness

The small number after each word is its number of syllables (event² = 2 syllables).