The story
Uitwaaien is a Dutch verb made from uit, 'out', and waaien, 'to blow', as the wind does. It means going out into windy weather, usually somewhere open like a beach or a dyke, to clear your head. The wind does the work: you come back red-cheeked and lighter.
The Dutch treat it as an ordinary weekend plan. On a grey Sunday in autumn, families drive to the coast to uitwaaien, walk along the tideline leaning into a gale and finish with soup or hot chocolate in a beach pavilion. Nobody thinks this needs explaining. A colleague who says on Monday that they went uitwaaien has said everything.
What makes it hard to translate is that English has the parts but not the whole. You can blow away the cobwebs or clear your head, but neither insists on wind. Uitwaaien does. A calm, sunny walk is just a walk.
The verb has a small grammatical quirk: Dutch speakers use both a regular past tense, waaide uit, and the old strong form, woei uit, and dictionaries record both.
A scene: the dyke at Petten on a Sunday in November, wind force seven from the west. A father and two children walk with their coats flapping, shouting to hear each other over the gusts. After half an hour the youngest has stopped complaining and is laughing at nothing. Back in the car, with the heater on, the father says: 'Lekker uitgewaaid.'