The British spelling of the present participle of 'geometrize,' meaning to make something have a geometric shape or to apply geometric principles to something.
From geometrize (from geometry + -ize suffix), which comes from Greek geometria (geo- 'earth' + metria 'measurement'). The -ising ending is the British variant of the American -izing.
The difference between 'geometrising' and 'geometrizing' is purely a spelling convention that divides American and British English—yet both words describe the same ancient human impulse to find mathematical patterns in nature, something that fascinated everyone from Euclid to the architects of Islamic mosaics.
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