To move fast with a soft rushing sound — the sound of air or water sliding past. A car whooshes by on a wet road; a train whooshes into the station; the doors of a lift whoosh open. It is also a noun: 'a whoosh of cold air came in when he opened the door.' And people say it on its own, as a sound effect, the way we say 咻 in Chinese: 'And then — whoosh! — it was gone.' The word is a picture of its own sound. That gives it a light, almost playful feeling, so you meet it in stories, in advertising, in speech, and in writing that wants you to feel the movement. It is not a formal word; you would not write it in a business report. Notice which sound it is: a whoosh is soft and airy, not sharp. A rocket, wind, a passing car, a big skirt, a sword swung through air — these whoosh. Something hitting something else does not; that is a bang or a crash. Because it is a sound word, English lets you stretch the vowel when you say it for fun: 'whoooosh'. Your phone probably makes a whoosh when you send an email — that is the same word, and that is why the sound was chosen.