The Collaborative International Dictionary of English v.0.48:

Misdeem \Mis*deem"\, v. t.
   To misjudge. [Obs.] --Milton.
   [1913 Webster]

Easton's 1897 Bible Dictionary:

Misdeem
   (Deut. 32:27, R.V.). The Authorized Version reads, "should
   behave themselves strangely;" i.e., not recognize the truth,
   misunderstand or mistake the cause of Israel's ruin, which was
   due to the fact that God had forsaken them on account of their
   apostasy.