The present participle form; the ongoing action of persuading someone not to do something.
From dissuade + -ing (present participle suffix). This form describes an action in progress or a habitual action, as in 'She is dissuading him from the plan.'
The -ing form is grammatically important because it lets English speakers talk about actions as processes rather than completed events—'dissuading' emphasizes the persuasion happening over time.
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