rustiest

adjective
  1. 1

    Marked or corroded by rust.

  2. 2

    Of the rust color, reddish or reddish-brown.

  3. 3

    Lacking recent experience, out of practice, especially with respect to a skill or activity.

  4. 4

    Of clothing, especially dark clothing: worn, shabby.

  5. 5

    Affected with the fungal plant disease called rust.

Source: https://en.wiktionary.org/wiki/rustiest, https://en.wiktionary.org/wiki/rusty