The HostileTeacher is the teacher (or the individual who ''thinks'' he is the "teacher", such as a person who views himself more knowledgeable on the topic at hand than his opponent in a debate) who holds the student(s) in contempt.  Not just HostileStudent''''''s, or students that would rather not be there--but ''all'' students.  Such teachers frequently get annoyed or hostile when the student offers even the slightest challenges to what they are teaching, whether it may be outright disagreement, inquisitiveness outside the lessons, etc.  

Note that "hostile" here doesn't mean "rigorous" or "difficult"; instead it refers  to an attitude of superiority and/or contempt.  A hostile teacher might nonetheless be an easy grader; whereas a teacher might pay the utmost respect to her students by holding them to high standards on tests and such.

Often times, the HostileTeacher has encountered one or more HostileTeacher''''''s when he or she was a student, and learned the lessons well.  In some fields of study; it is assumed that the teacher/student relationship ''should'' be hostile--it is the duty of the student to put up with it; the hostility is for their own good, after all; and it is the privelege (and duty) of the teacher to be hostile to ''his'' students when acquiring that rank--because that is the ''proper'' way to teach.

Sometimes, a hostile posture may be appropriate in an academic setting, in particular for material which is well-established and well-known to be true.  Arguments that 2+2 is not 4 are more likely to be disruptive than enlightening.  Other times, the hostile posture can be detrimental to the learning process, especially in fields of study where curiosity or inquisitiveness is a ''good'' thing; or where there exist open problems, or where there cannot be a right answer.  

In a non-academic setting (such as debates here on Wiki), being a HostileTeacher (or a HostileStudent for that matter) is often corrosive.  It can often be a way of trying to win/end a debate via intimidation--"shut up, you're not qualified to debate me".  It can also be rather insulting in a forum of professionals; many of whom will not take a HostileTeacher attitude lightly from someone they perceive to be a peer rather than a superior.

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Sometimes somebody who is too lazy to present their evidence well acts like a HostileTeacher.

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See also HostileStudent, SelfStandingEvidence.