ilegible

adj. illegible, unreadable, undecipherable

= illegible, unreadable.
Ex: 13% of the microfiche had illegible areas.
Ex: The purportedly 'permanent' CD-ROM medium follows the immutable laws of nature: the aluminum coating on the disc oxidises over time (a condition called disc rot or CD rot), resulting in an unreadable disc.
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* volverse ilegible = become + unreadable.