another acceptable translation is gas. as in after you have a large meal of bean, cabbage and cheese. this is where the no-touch throw stuffs come about. it's deadly at 10 paces in enclosed space. the counter for this ki is to open all the doors and windows, might want to kick in the big fan too. but whatever you do, DO NOT light a candle or use any sort of open flame!
have you ever wonder why we wear the hakama? it really is a device to contain and slow dispersing the ki leak during practice; thus the two big vents on both side of the hips.
I'm sure your partners can feel when you lose it too *cough* or perhaps there's another sense involved. Tip o' the hat to Phi. "Losing ki", wow, that's...one way to put it. "Wow, Mary just lost her ki, open the window!"
Christian - Should you continue your pursuit of Ki development in conjunction with your Aikido, you'll surely run into more nonsensical, ill informed derisive, views such as those above. Aikido people come in all stripes and as you will find "there are none so blind as those who will not see". (John Heywood)
Don't let the foot stompers sway you, there's a lot more to Aikido than technique.