/næb/
[verb] To catch or arrest someone suddenly, especially a criminal; also used informally to mean grabbing or taking something quickly.
The word 'nab' is thought to share ancient roots with 'kidnap' — both words carry the idea of a sudden, secret grab.
The word 'nab' appears in English records from around the late 17th century, roughly the 1680s, as a piece of slang used in criminal and low-life circles. Its exact origin is surprisingly hard to pin down, which is fitting for a word so associated with stealth and sudden action. Most etymologists point to a Scandinavian source, likely related to the dialectal Norwegian and Swedish words 'nappa' and 'nappa', both meaning to catch, snatch, or grab. These Scandinavian terms entered the English-speaking world through the long history of Norse settlement and trade along Britain's northern and eastern coasts.
The deeper root behind these Scandinavian forms is thought to be a Proto-Germanic base meaning to seize or grip suddenly — a root that gave rise to several related words across the Germanic language family. It is closely connected to the Low German word 'nappen', meaning to snatch, and possibly to the Dutch 'nappen' as well. These words all share the same core sense of a quick, decisive physical action, the hand closing around something before any resistance is possible.
Interestingly, 'nab' belongs to the same family of thought as the word 'kidnap', which dates from almost exactly the same period. 'Kidnap' is formed from 'kid', an old slang term for a child, and 'nap', a variant of 'nab' meaning to steal or snatch. So 'nap' and 'nab' were essentially interchangeable in 17th-century London criminal slang, and 'kidnap' preserves that older form 'nap' frozen inside it like an insect in amber.
When 'nab' first appeared in written English, it was firmly part of the language of thieves, constables, and the London underworld. It was used both for the act of catching a criminal and for the act of stealing something. A thief could 'nab' a purse; a constable could 'nab' a thief. This double meaning — to steal and to catch a thief — reflects how the same word could describe both sides of the criminal world, depending on who was using it.
Over the following two centuries, 'nab' gradually moved out of pure slang and into more general informal usage. By the 19th century it appeared regularly in newspapers and popular fiction without any particular sense that it was criminal language. Today, it carries only a light, breezy informality — you might 'nab' a seat on a busy train, 'nab' a bargain in a sale, or see a detective 'nab' a suspect in a thriller novel. The word has kept its sense of speed and surprise, but lost almost all its gritty, underworld edge.