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.
To sock someone means to hit them. This is the case in Ireland, in England or in the States. Nobody knows where this expression comes from. It first appears in English around 1700.
Daniel Cassidy, author of the work of false etymologies, How The Irish Invented Slang, tries to match this to an available word in Irish. His chosen candidate is the word sac or sacadh, which is a verb derived from French sac, either directly or through English sack. It means to thrust something into a bag, to shove something, to stick something into or through something.
It doesn’t mean to hit someone or something hard, or indeed to hit them at all, so I can’t really see why it would be a suitable candidate for the origin of sock. Cassidy thought it could mean to hit someone because he misunderstood the meaning of poke, which originally meant a bag or sack.