This also sparked off controversy among linguists, with some claiming it wasn't even a proper word (the linguist Geoff Pullum said it was a "ordinary nominal with a participle functioning as attributive modifier of a noun". Just in case you wondered why).
OED defines it as "the section of society [...] particularly affected by inflation, wage freezes, and cuts in public spending during a time of economic difficulty, consisting principally of those people on low or middle incomes". OED picked it up from an interview by a leading Labour Party politician in the UK.
Which politician?