Actually, no.
verb (used without object) 1. to fail to maintain a desired pace or to keep up; fall or stay behind
a5cent is actually correct. Lag is the screen response to your input, not from switching between apps.
Firstly, I'd like to disclose that I am a long-time Android user who also happens to be a fan of what Microsoft has done of late and will almost certainly be switching to WP8 in the near future.
With that said, as intelligently as you and a5cent articulated your thoughts I feel that they are misguided. 11B1P, the generic definition you quoted provides 0 evidence that the term "lag" relates to screen response. Moreover, dictionary definitions and the denotation of words are rather useless when applied in a vacuum. Connotation, the perceptive meaning of a word is what truly matters.
So, socially speaking, from an individual who is very much in the "tech sphere," the term
lag is typically used to refer to an
unexpected delay. This word is often used in gaming to refer to degraded network or GPU performance. In computing it is typically used to discuss poor software operation as related to both hardware
and/or software. In networking it is used to describe poor network performance. In video capture it is typically associated with low frame rates. The list continues in this fashion. It should be noted that in every single one of these instances the term
lag is used colloquially and doesn't have a proper technical definition.
It is because of this that MAJ71303 has a point when saying that
"lag is subjective" and dependent
"on the person's perception." For example, someone who upgraded their computer from a Core i3 to a Core i7 would likely describe the change as going from "normal" to "fast." Someone who did the exact opposite and downgraded their computer from an i7 to an i3 would likely describe the change as going from "normal" to "slow" or "laggy." Let's remember that while the word
delay can be concisely defined as something which isn't instantaneous the word
lag is subjective. None of the realms it is applied to will ever be instantaneous, but when used it typically indicates an increased delay from what is expected or considered normal, which is a subjective frame of reference.
All that aside, I'd say that MAJ71303 is utterly wrong to dismiss everyone's commentary on WP8's "lag-free" environment because, while the wording is a bit misleading, it is mostly true by comparison. What I mean is, regardless of what your frame of reference for "lag" is, a comparable piece of hardware on WP8 has less unexpected delays than it's Android (or even iOS) counterpart.
I can honestly say that as an avid Android user for over 4 years who has always sought performance in the best hardware and the cleanest OS variants possible (mostly custom ROMs for my rooted Android phones) I was thoroughly impressed by WP8's performance when I tested a mid-range WP8 demo phone at a local store.