Force majeure：不可抗力，与作为法律拉丁语的「不可抗力」〔vis major〕含义相同。
是指不能预见、不能避免并不能克服的客观情况。不可抗力的来源既有自然现象（natural phenomena），如地震、台风，也包括社会现象（social phenomenon），如军事行动。作为人力所不可抗拒的强制力，具有客观上的偶然性和不可避免性，主观上的不可预见性以及社会危害性。
Act of god：天灾;不可抗力
是指无法合理预见或预防的特殊自然事件(如洪水或地震)，Act of god与Force majeure 有所不同，Force majeure不仅包括自然力，还包括人为力量，Act of god 只表天灾。
Fortuitous event：偶然事故;意外事件。
在法律英语中，Fortuitous event指无法合理预见或预期的自然或人为事件，并且超出了当事人的控制范围，如闪电、地震等事件。
参考双语例句：
In that respect, the court based its decision on the Supreme Court judgement of 17 January 2008 (http://turan.uc3m.es/uc3m/dpto/PR/dppr03/cisg/espan67.htm) (CLOUT case No. 802) which stated that “fundamental breach corresponds to the rule of fundamental breach of contract and from it is derived a system of contractual liability based on a criterion of objective imputation, attenuated, however, by exceptions— corresponding to the hypotheses of fortuitous events and force majeure under domestic law — and by a parameter of reasonableness (article 25 in fine)”; accordingly, the Navarra Provincial High Court considered that it did not appear in the case in question that any such lack of predictability of the outcome would create a situation that could be regarded as a fortuitous event or one of force majeure.
在这方面，法院的决定基于2008年1月17日最高法庭的判决（http://turan.uc3m.es/uc3m/dpto/PR/dppr03/cisg /espan67.htm）（《法规判例法》判例 802）。判决指出“根本违约即为根本违反合同规则，根据此规 则可推出一个以客观推定标准为依据的合同责任制度，但可以根据除外情况——类似于国内法关于偶发事件和不可抗力的假设——及合理性因素减轻责任（第 5条最后）”；因此，纳瓦拉省高级法院认为，在本案中，结果可预见性的任何如此缺乏似乎都不会造成一种可视为偶然事件或不可抗力的情况。
he wrongfulness of an act of an international organization not in conformity with an international obligation of that organization is precluded if the act is due to force majeure, that is, the occurrence of an irresistible force or of an unforeseen event, beyond the control of the organization, making it materially impossible in the circumstances to perform the obligation.
国际组织违反其国际义务的行为如起因于不可抗力，即起因于该组织无法控制的不可抗拒的力量或无法预料的事件，以致该组织在这种情况下实际上不可能履行义务，该行为的不法性即告解除。
there shall have occurred any event or series of events (including without limitation the occurrence of any local, national or international outbreak or escalation of disaster, riot, public disorder, civil commotion, fire, flood, explosion, outbreak of an infectious disease, calamity, crisis, strike, lock-out, hostility, insurrection, armed conflict, act of terrorism, act of God or epidemic)
应已出现任何事件或连串事件（包括但不限于任何地方、全国或 际灾难、暴乱、公众*乱、*乱、火灾、水灾、爆炸，传染病爆发、灾害、危机、罢工、停工、敌对行动、叛亂、武装冲突、恐怖 活动、天灾或疫症的发生或升级）
来源：译问
