indecipherable

Etymology

From in- + decipherable.

adj

1. Not decipherable; impossible to decode, read, understand or comprehend.
   The doctor's handwriting was indecipherable.
   The second and third quarters of the shield are indecipherable on the stone but clearer in two other representations of the arms, a painted wooden funeral hatchment for Mary Davie[…] 8 October 2012, Daniel W. Patterson, The True Image: Gravestone Art and the Culture of Scotch Irish Settlers in the Pennsylvania and Carolina Backcountry, UNC Press Books, page 141
2. Indistinguishable
   The explanation some are suggesting is that the object takes on the appearance of what is behind it, or that it takes on the appearanec of what the observer thinks is behind it. In both cases, the object is still visible. It's a visible representation of what's behind it, but it is still invisible, just indecipherable from its surroundings. 22 December 2001, Michael A. Norville, “Why do so many DMs hate their players”, in rec.games.frp.dnd (Usenet)
   If you knew who Jerry was you'd swear you'd been cloned. Your posting style is virtually indecipherable from his. 21 April 2004, RoyWilliamsIsGay, “Pablo the Troll”, in alt.sports.football.pro.phila-eagles (Usenet)
   A British university compared lads mags with comments from convicted rapists. It found that people could not distinguish the source of the comments. That is, Zoo users' language practically indecipherable from that of sex offenders. 20 May 2015, Laura Pintur, “My campaign against Zoo Magazine: the well-being of girls should come before profits” (0:25 from the start), in Guardian Australia