Often refers to hybrids between ales (fermented near room temperature with top-fermenting yeast strains) and lagers (fermented cold with bottom-fermenting yeast strains).
Like California Common beer (Anchor Steam), which uses a lager yeast but at ale temperatures, or German Altbier, which ferments pretty cold (mid-50s, I think) with an ale yeast.
I'd need more context to know exactly what you're talking about, though.
EDIT: SB beat me to it.