Alibi
From 'Vocabulary' part of The ABC Of Plain Words by Sir E Gowers (1951)

There is still a minority of our membership which has failed to recognise its new responsibilities. It is not sufficient to point to certain shortcomings of the National Goal Board to create an alibi.
Members of the timber trade, like members of any other trade, are glad of any alibi to explain any particular increases in price.
Either we accept the bare facts or we go down to a lower standard of living. The day of alibis is gone.

Do not use alibi as it is used in these examples, in the sense of excuse, or of an admission of guilt with a plea of extenuating circumstances, or of throwing the blame on someone else. Alibi is the Latin for elsewhere. To plead an alibi is to rebut a charge by adducing evidence that the person charged was elsewhere at the time of the act alleged against him. " Oh Sammy Sammy vy vornt there an alleybi? " cried old Mr. Weller at the conclusion of Bardell v. Pickwick (in which it was beyond dispute that Mrs. Bardell had been found in Mr. Pickwick's embrace) and so furnished a classic example of the confusing properties of this word.