Present participle of antiquate; the process of making something outdated or old-fashioned; can also function as an adjective describing something that causes obsolescence.
From antiquate plus the present participle suffix -ing. The -ing form can be used as a verb (progressive aspect) or as an adjective/noun (gerund).
The -ing form is doing double duty here: it's both an action (the laptop is antiquating your desktop) and a quality (those antiquating technologies). English grammar lets one word shape-shift between different jobs.
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