Other forms: circumstances
A circumstance is one of the conditions around an event, a fact that shapes what happens without being the thing itself. He was late, it was raining, the shop had already shut: those are the circumstances.
The plural does nearly all the work. You say under the circumstances or in the circumstances when you are explaining a decision, and under no circumstances when you are forbidding something outright, as in under no circumstances open that door. Circumstantial evidence is proof built out of surrounding facts rather than somebody seeing it happen. Older writing gives you reduced circumstances for a family that has lost its money, and a victim of circumstance for someone blameless whom events simply landed on. The singular on its own sounds legal and formal, so in speech people reach for the plural almost every time.
1nouncircumstanceA fact or condition surrounding an event and affecting how it turns out.
“The judge took every circumstance of the case into account.”
2nounlifeCircumstances: the conditions of someone's life, especially their money.
“Her circumstances changed the year the factory closed.”
circumstance is a surrounding condition.
Circumstance came in from Latin circumstantia by way of Old French circonstance and Middle English circumstaunce. The spelling took its time, with the -staunce ending holding on for centuries. The meaning has hardly moved at all.
Latin
circumstāntia
Old French
circonstance
Middle English
circumstaunce
English, today
circumstance
From Middle English circumstaunce, from Old French circonstance, from Latin circumstāntia. From Middle English circumstaunce, from Old French circonstance, from Latin circumstantia.
Etymology from Wiktionary, CC BY-SA