Actually it has several answers, some of which include +i, -i, +j, -j, +k, -k, if you're working in the quaternions, for example. It also means otherwise intel

Actually it has several answers, some of which include +i, -i, +j, -j, +k, -k, if you're working in the quaternions, for example. It also means otherwise intelligent and erudite people who aren't mathematically inclined won't be able to comment, which seems a shame.