/smæk/
[verb] To hit someone or something with a sharp, loud blow, usually with an open hand. It can also mean to press your lips together and then open them quickly, making a loud sound to show that food tastes good.
The satisfying 'smack' of lips tasting food is older than the slapping sense — this word began in the mouth, not the hand.
The story of 'smack' is really three stories wound together, and untangling them reveals just how richly layered a simple four-letter word can be. The oldest thread belongs to taste and sensation. Old English had the word 'smæc', meaning a flavour or taste — the quality something leaves on your tongue. This word descended from Proto-Germanic *smakwaz, which also produced Middle Low German 'smak' and Old Dutch 'smāc', all carrying the same sense of savour or relish. When someone spoke of the 'smack of the sea' or the 'smack of garlic', they were using this ancient, sensory word.
From taste, the word drifted naturally toward the lips themselves. By the 16th century, 'smack' had come to describe the action of pressing the lips together and separating them with a sharp, audible pop — the universal gesture of appreciating good food, or of giving a hearty kiss. This is where the word 'smacker', meaning a loud kiss, comes from. The sound a person makes while savouring something delicious was so vivid and recognisable that the word essentially became onomatopoeic — it started to sound like exactly what it described.
The 'hitting' sense emerged as a natural extension of that sharp, cracking sound. If the snap of lips could be a smack, then any sudden, crisp blow — especially one that made a similar noise — deserved the same name. By the mid-17th century, 'smack' was firmly established as a verb meaning to strike with an open hand, producing that distinctive flat crack. The sound, not the pain, was at the heart of the word. This is why we say something 'smacks into' a wall, or that a ball 'smacked' against the floor — the emphasis is always on the sharp, decisive noise of impact.
There is also a nautical 'smack' that runs alongside all of this, entirely unrelated in origin. A smack was a type of small single-masted sailing vessel used for fishing, especially along the coasts of Britain and the Netherlands. This word came from Dutch 'smak', itself derived from 'smakken', meaning to fling or throw — perhaps describing how such a nimble boat cut through waves. This nautical usage was common throughout the 17th, 18th, and 19th centuries, and while it has faded today, it once filled the pages of seafaring logs and harbour records.
In modern informal English, 'smack' has also become slang for heroin, a usage that appeared in American English in the 1940s and is thought to derive from Yiddish 'schmeck', meaning a sniff, which itself came from German 'schmecken', meaning to taste or smell — bringing the word's journey remarkably full circle, back to its oldest meaning of sensory experience. Few words in English manage to connect a Viking sailor's fishing boat, the pleasure of a good meal, a parent's disciplinary tap, and the streets of mid-century New York quite so effortlessly.