nonassumption

noun3

1. •
   The failure to accept as true without proof.
2. •
   Something that is not assumed to be true without proof.

   • Understanding the playing field, including assumptions and nonassumptions. — 2012
3. •
   The failure to take up, adopt, or take responsibility for.

   • Nonassumption of marital name by alleged wife tends to show no marriage. — 1916