late 14c., dasen, "be stunned; make bewildered," perhaps from Old Norse *dasa (compare dasask "to become weary," with reflexive suffix -sk). Or perhaps from Middle Dutch dasen "act silly." Perhaps originally "to make weary with cold" (a sense in English from c. 1400), which is the sense of Icelandic dasask (from the Old Norse word). Related: Dazed.
"a dazed condition, state of being stunned or confused," 1825, from daze (v.).