Daniel Cassidy, the Great Fraud, informs us in his crazy book on the Irish origins of American slang that the word ice was formerly used by carnival folk as a term for the graft paid to local authorities to be allowed to perform in an area. We do not know where it comes from but Cassidy claims that it is derived from the Irish íos, meaning a minimum.
This is an absurd claim. Like uas (see Whiz) íos was once a word in the language but even if you look at works like Desiderius, written in the early 17th century, the word íos is not used as a word in its own right. In modern times, the word íos has been used as a prefix for minimum. Thus, where a native speaker would say an teocht is isle (the lowest temperature) in official or scientific documents you might use íosteocht for minimum temperature. However, íos is never used as a word in its own right and it would not even have been used as a prefix before the 1920s so Cassidy is completely wrong about this.