Homoglyph Domain
Quick answer
A lookalike domain using visually identical or near-identical characters — like rn for m, or Cyrillic а for Latin a — to impersonate a brand's domain.
Homoglyph attacks evade casual inspection and even some automated filters, making them favorites for phishing. Detection requires generating and monitoring the homoglyph space of your domains; enforcement follows the standard registrar/UDRP path.