Defention is the act of defending yourself against someone else defending themselves. Such as someone hitting you in defense and you hit them back in defention.

without doubt (used for emphasis).

synonyms: definitely, certainly, Surely, for sure, unquestionably, without doubt, without question, undoubtedly, indubitably, positively, absolutely; undeniably, unmistakably, plainly, clearly, obviously, patently, palpably, transparently, unequivocally

¯\_(ツ)_/¯

This is how a retard spells definitely.