In a manner that cannot be read.

ऐसे तरीके से जो पढ़ा न जा सके।

English Usage: The doctor's handwriting was so poor that he wrote the prescription illegibly.

Hindi Usage: डॉक्टर की लिखावट इतनी खराब थी कि उसने प्रिस्क्रिप्शन को पढ़ने के लिए illegibly लिखा।