To make something resemble death or appear deathlike; to treat something as if it were dead.
From death + -ify suffix (meaning to make or cause to become). The -ify suffix comes from Latin -ficare (to make), seen in words like beautify, clarify, and petrify.
The -ify suffix is a powerful word-building tool in English: add it to almost any noun and you can make it a verb meaning 'to cause it to become that thing'—'deathify' means to make something look dead.
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