首先我们在Investopedia搜索到了这四个词的各自英文解释：

force majeure:

Force majeure is a clause that is included in contracts to remove liability for unforeseeable and unavoidable catastrophes that interrupt the expected course of events and prevent participants from fulfilling obligations. These clauses generally cover natural disasters, such as hurricanes, tornadoes, and earthquakes, as well as human actions, such as armed conflict and man-made diseases.

vis major:

Vis major is a Latin term that means "superior force" and describes an irresistible natural occurrence that causes damage or disruption and that is neither caused by nor preventable by humans—even when exercising the utmost skill, care, diligence, or prudence.

Examples of vis major include hurricanes, tornadoes, floods, and earthquakes. The terms act of God, natural disaster, and force majeure are synonymous with vis major. These terms are commonly used in contracts to exclude one or both parties from liability and fulfilling their contractual obligations when events beyond their control occur.

act of god:

An act of God describes an event outside of human control or activity, such as a natural disaster like a flood or an earthquake.

In business, the phrase “act of God” is not associated with any particular religion or belief system. Contractual language referring to acts of God are known as force majeure clauses, which are often used by insurance companies. These clauses typically limit or remove liability for injuries, damages, and losses caused by acts of God.

contingency：

A contingency is a potential occurrence of a negative event in the future, such as an economic recession, natural disaster, fraudulent activity, terrorist attack, or a pandemic. In 2020, businesses were hit with the coronavirus pandemic forcing many employees to have to work remotely. As a result, companies needed to implement a remote work strategy. However, for some businesses, working remotely wasn't an option, which led to the implementation of enhanced safety measures for employees and customers to prevent the spread of the virus.

西文法律术语force majeure原用于海事保险领域，后逐渐扩大至商业合同。该词实为大陆法系术语，与拉丁文vis major和西班牙文fuerza mayor相近，较晚才在普通法系得到广泛运用，在英国法中并没有不可抗力(Force Majeure通常简称为FM)的一般概念，需在合同里明示约定，且其适用取决于该条款的具体措辞。

Vis major意为“不可抗之力量”（superior force），与force majeure几乎同义。英国法院很早就对该术语有明确的定义——既包含天灾等自然灾害，还指人力可以干预的事件，如战争、罢工等，故如今很难对二者做有意义的区分，实践中可以互用。

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英文act of god属普通法之概念，《元照英美法词典》译为“天灾”和“不可抗力”，并谓“没有人力干涉，完全由自然力导致的事件。”英国法官将act of god清楚定义为包括自然灾害等在内的人力无法干预的自然事件，包括水灾、台风、海啸、地震及火山爆发等，并且不等同于“无法避免的事件”（inevitable accident）。如新冠肺炎等疫情，并非自然力所造成的没有人力干涉的事件，不属于天灾的范畴。

Contingency是指“未来事件”、“意外事件”及“偶发事件”，可以视为对“不可抗力”范围内发生之具体情形的表述，不必然构成“不可抗力”下的事由，范围当属最宽。

来源：译问