the act or process of contracting or developing bejel disease.
Present participle of 'bejel' formed with the -ing suffix, following standard English gerund formation rules.
Medical verbs like 'bejeling' are actually quite rare in English—we usually say 'contracting bejel' rather than 'bejeling.' The fact that this form exists shows the flexibility of English morphology, even if doctors wouldn't commonly use it.
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