Once I knew two types of "lag": - input lag (display <-> source), when I play offline and my input doesn't work immediately; - online/LAN lag (source <-> source), when I play online and my input doesn't work immediately. Lag = input doesn't work immediately, due to latency. But in this forum I feel like lag is also stutter or unstable framerate or something else. These things could cause problems (input lag, too), but are not the problem! Am I wrong?
Lag is to do with network, but people use it to mean frame rate drops etc. Offline lag isn't called lag, it's called input delay, or something like that.
I talk about people talking about iPhone/iPod games. Yes, you are right, but input lag is now universally recognized: http://en.wikipedia.org/wiki/Input_lag
Lag is something that can only happen online. Offline, an unstable framerate can be described as "slowdown" there are a lot of people on these forums who are simply misinformed and don't realize that they are using incorrect terminology. An offline game cannot "lag."