1. in a way that is impossible or very difficult to read, understand, or interpret
Usage: formed from the adjective 'indecipherable' with the adverbial suffix '-ly'

Examples

• The doctor's handwriting was indecipherably messy on the prescription.
• She spoke so quickly and indecipherably that no one could follow her argument.
• The ancient text was indecipherably faded after centuries of exposure.
• His notes were scrawled indecipherably across the margins of the book.
• The code was indecipherably complex without the proper decryption key.