For some time now, some of my on-line friends have advised me to provide a version of CassidySlangScam without the invective aimed at Cassidy and his supporters. In response to that advice, I am working on providing a glossary of the terms in Cassidy’s ludicrous book How The Irish Invented Slang with a short, simple and business-like explanation of why Cassidy’s version is wrong.
Daniel Cassidy, in his work of false etymology, How The Irish Invented Slang, claimed that jiffy, as in the phrase “in a jiffy”, comes from the Irish deifir, which means hurry. This claim is certainly better than Cassidy’s usual standard. Deifir does sound a bit like jiffy, especially in an Ulster pronunciation. And the meaning is similar, though not identical. However, there are problems with Cassidy’s claim.
While the origin of jiffy is unknown, it seems to have been a cant term used by thieves in the late eighteenth century in England. It is thought that jiffy or giffy was cant for lightning. It may be related to dialect terms like gliff, which can mean a sudden light. There is very little Irish influence on English criminal cant, though there is some. And while the term deifir is similar in meaning to jiffy, it is not a perfect match. Nobody in Irish would ever use the preposition in with deifir – in a hurry is faoi dheifir in Irish. Focloir.ie gives a number of expressions for the similar expression in two shakes (of a lamb’s tail): i bhfaiteadh na súl, ar an bpointe boise, ar iompú do bhoise, in áit na mbonn, i mbomaite. It is hard to see why Irish speakers would not have used an expression like this rather than a word meaning “hurry”.