In Daniel Cassidy’s insane and inane book, How The Irish Invented Slang, Cassidy tried to prove that hundreds of words in English derive from Irish.
His methodology was simple: he hunted through Irish dictionaries to find a word which resembled the target word in English. When he couldn’t find anything suitable (which was usually the case), he took two or three Irish words and combined them into a ‘well-known phrase’ which had never been used in Irish, and for which Cassidy was happy to provide a fake definition.
Occasionally, Cassidy found words which seemed a good fit (at least for some of the meanings) but made no attempt to establish whether they were loanwords into Irish or loanwords from Irish to English.
Cassidy claimed that the word gaff meaning a boat-hook comes from the Irish gaf or geaf. However, gaf or geaf really comes from English and English got the word from Provencal gaf via French. The word gaffe meaning a blunder, is the same word. A quick search on the free and fully-searchable Electronic Dictionary of the Irish Language will confirm that gaf/geaf is not an ancient word in Irish. It is plainly, obviously and clearly a loanword.
Incidentally, the unrelated word gaff meaning a home or a place is from Romani gav.
I leabhar amaideach, craiceáilte Daniel Cassidy, How The Irish Invented Slang, rinne Cassidy iarracht a chruthú gur tháinigh na céadta focal i mBéarla ón Ghaeilge.
Bhí a chuid modhanna simplí: chuaigh sé a chuardach i bhfoclóiri Gaeilge le focal a aimsiú a bhí cosúil leis an sprioc i mBéarla. Nuair nach bhfuair sé a dhath (rud a tharla níos minice ná a mhalairt), fuair sé dhá fhocal nó trí fhocal i nGaeilge agus chuir sé le chéile iad le ‘frása coitianta’ a chruthú nach raibh riamh ann i nGaeilge, agus bhí Cassidy sásta sainmhíniú bréige a chur ar fáil fosta.
Ó am go ham, thagadh Cassidy ar fhocail a bhí fóirsteanach i gcosúlacht (maidir le cuid de na ciallanna, ar a laghad) ach ní dhearna sé iarracht ar bith a fháil amach an iasachtaí a fuair an Ghaeilge ó theanga eile a bhí iontu, nó iasachtaí ón Ghaeilge sa Bhéarla.
Mar shampla, rinne Cassidy iarracht a mhaíomh go bhfuarthas an focal Béarla gaff, a chiallaíonn crúca báid, ón Ghaeilge gaf nó geaf. Is é fírinne an scéil, áfach, go bhfuair an Ghaeilge na focail gaf nó geaf ón Bhéarla, agus go bhfuair an Béarla an focal ón Phroibhinsis gaf tríd an Fhraincis. Is ionann é agus an focal Béarla gaffe, a chiallaíonn botún. Má dhéanann tú cuardach are DIL, foclóir Gaeilge atá saor in aisce agus atá go hiomlán inchuardaithe, beidh tú ábalta a dhearbhú nach focal seanbhunaithe sa Ghaeilge é gaf/geaf. Is léir agus is ríléir gur iasacht atá ann.
Dála an scéil, níl baint ar bith ag an fhocal seo leis an fhocal gaff a chiallaíonn baile nó áit. Is ón Romainis gav a tháinig an ceann sin.