1 adverb COMM excessivelyhouses are prohibitively expensivetá praghsanna tithe i bhfad ródhaorfuel is prohibitively pricedtá praghas an bhreosla i bhfad ró-ard, tá praghas an bhreosla chomh hard sin nach bhfuil daoine ábalta é a cheannach2 adverb impossiblythe course is prohibitively difficulttá an cúrsa i bhfad ródheacair, tá an cúrsa chomh deacair sin go gcuireann sé daoine ó dhoras