"Blood traitor" is a derogatory term commonly used by elite pure-blood families to describe witches or wizards who sympathise with the non-magical community and/or willingly associate with other such sympathisers or with Muggle-borns. Other similar terms include "Muggle-lover", "Mudblood-lover", "Dunglicker", "Scumsucker", as well as "Mudwallower", all of which refer disparagingly to those who are comfortable in the company of Muggles and/or Muggle-borns, whom prejudiced wizards and witches believe are dirty and inferior. The most notorious blood-traitor family was the Weasleys.