I don't have an OED to hand, but dictionary.com gives us:
1. combining or coordinating separate elements so as to provide a harmonious, interrelated whole: an integrated plot; an integrated course of study.
2. organized or structured so that constituent units function cooperatively: an integrated economy.
I've argued before that, when it comes to creative work, many agencies seem to think it means "make everything the same", the so-called "matching luggage approach".
What I've only recently realised is that somehow the term seems to have become synonymous with "Below the Line" or "Through The Line" when it's used to describe an agency.
This pisses me off for two reasons:
1) It's a category mistake. Integration is about the relationship between the part, not what those parts are.
Far and away the best integrated campaign I've seen in ages is largely ATL. The bits that aren't ATL are digital / cross-promotional. It's Volkswagen 'See Cinema Differently". You can see the whole thing here.
2) My AD and I have just come out of a long freelance booking. We've started hawking ourselves around, and somewhat naively, we made the mistake of describing ourselves as an "Integrated" team. I guess we had in mind stuff like the Volkswagen campaign.
But, as a result, we've had our book sent to a bunch of very tactical, very DM-focused agencies. No disrespect to them, but adapting a creative strategy handed down to you from another agency does not make you integrated.
It's also not really where our skill-set lies, so I can't see them being that interested in us.
So it's a bit of a waste of everyone's time. really.