From 14th Century Latin trusti = "a blood pact, oath or alliance". The word "rus" in Latin meaning "country, village, land" and also meaning "blood" in certain slavic languages. 

The claim of the word "trust" being from as early as the 12th Century from Old Norse origins is deliberately misleading. In its strictest sense, a trust is a fictional religious and legal concept --therefore a Trust does not exist unless some formal oath, pact and agreement exists in good faith.