A person posting in an online forum in a way which is stupid, for example by exposing himself or herself to disciplinary or legal action by making offensive or libeleous comments.

Typically the commentard will try to be anonymous but reveal himself through logged IP adresses that resolve back to his employer or by otherwise inadvertently giving out identifying information.
''A commentard using the handle Scrutineer tore into research that demonstrated how it might be possible to make a PIN authorised transaction'' - The Register

''Colorado man faces jail for being a commentard'' - J.P. Weichel - Gawker
by Morthandeus February 24, 2010
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