I'm going to *guess* that Emma spelled it that way, one letter less in length, to get the text of the dialog to fit on-screen. She had to do that several times in the Oblivion version.
"We're going to change the terms of engagement. It's our war, not theirs. We don't need cities or armies, we have the cells of human bodies: an invisible weapon for an invisible war" - opening cinematic of Deus Ex: Invisible War