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.
The word twerp, an insulting term for an insignificant person or fool, seems to make its appearance first in English about 1910. Nobody is quite sure of its origin. A popular derivation is that it derives from the name of T.W. Earp, an Oxford student who was very aesthetic and artistic and mocked by his sportier contemporaries for his urbanity. The Dictionary of American Slang suggests that it was first used in 1874 (which would discount the T.W. Earp explanation) but apparently there is no citation for this, so I would be reluctant to accept it without further information.
In his etymological hoax, How The Irish Invented Slang, the late Daniel Cassidy claimed that the expression twerp comes from the Irish word doirb, which he defines as ‘an insect, a worm, a dwarf, a small, insignificant person, a diminutive insignificant creature; a small fish, a small fry’.
Doirb, according to Ó Dónaill’s Foclóir Gaeilge-Béarla (Irish-English Dictionary), means a water beetle. That is the only meaning given.
Dinneen, an earlier and less accurate dictionary, has a head-word doirbh, which means: an insect, causing swellings in cattle or soreness of the teats; a water-worm (Torr); a dwarf. It can also have the forms doirb, duirb, dairb or darbh.
In other words, doirb, which would be pronounced dorrib, or doirbh which would be pronounced dorriv, is basically a word for a water-beetle. Apparently it can also mean a dwarf but its use as an insult for an insignificant person is not recorded anywhere before Cassidy.