/bloʊ/
[verb] To move air outward from the mouth or to cause air to move with force. It can also mean to make a sound using a wind instrument, or — as a noun — to describe a hard hit or a sudden shock.
The same ancient root that gives us 'blow' also secretly hides inside the word 'bladder' — both descend from the idea of swelling with air.
Few words in English carry as much raw, physical energy as 'blow,' and its origins go back to some of the oldest layers of human language. The word descends from the Old English verb 'blāwan,' meaning to send out a stream of air, to breathe, or to make wind. This was already a well-established word by the time of the earliest written English texts in the 7th and 8th centuries. It belonged to a strong Germanic verb class, which is why even today we still sometimes hear the irregular past tense 'blew' instead of a simple 'blowed' — a living fossil of the verb's ancient grammar.
Tracing further back, Old English 'blāwan' connects to the Proto-Germanic root '*blēaną,' a reconstruction that linguists use to describe the shared ancestor of the Germanic language family. From that same Proto-Germanic source came Old High German 'blāen' and Old Norse 'blása,' both meaning essentially the same thing: to blow, to breathe, to puff. This tells us that long before English, German, and the Scandinavian languages separated into distinct tongues, speakers across northern Europe already shared this word for moving air.
Go back even further, and you reach the Proto-Indo-European root '*bhleh₂-,' which carried the broad sense of swelling, inflating, or puffing up. This root was enormously productive. Through Old English, it gave us not only 'blow' but also 'bladder' — literally a bag that swells with air or liquid — and 'blast,' which entered Middle English from Old Norse 'blást,' meaning a gust of wind. The Latin branch of the same Indo-European family produced 'flāre,' meaning to blow, which fed into English much later through words like 'inflate' (Latin 'inflāre' → English 'inflate') and 'flatulence' (Latin 'flātus' → English 'flatulence'). So hidden inside even the most polite medical vocabulary is the same ancient breath of air.
The word 'blow' in the sense of a hard physical strike — as in 'a blow to the head' — has a somewhat murkier history. This meaning appears in Middle English around the 15th century, likely borrowed from or influenced by Middle Low German 'blaw' or Middle Dutch 'blouwe,' both meaning a strike or hit. It is possible that this meaning developed independently from a different root, though some scholars argue it may be a figurative extension of the original 'blow' — imagining a hit as something that strikes like a sudden gust. The two meanings have coexisted in English for so long that most speakers never notice they might come from different directions entirely.
Over the centuries, 'blow' has expanded into an extraordinary number of idioms and compound words. To 'blow one's own trumpet,' meaning to boast about oneself, has been in English since at least the 16th century. 'Blowout,' 'blowback,' 'blowfish,' and 'blown' all spin off from the core idea of air in motion. In informal modern English, 'blow' can also mean to waste or ruin something — 'she blew her chance' — a figurative leap that imagines opportunity being scattered by the wind. This constant reinvention is a mark of a truly old, deeply embedded word: it keeps finding new meanings because it connects to something fundamental in how we experience the physical world.