Today it means: In fiction and art, a diapersuit (“insulated full-body suit, usually made out of rubber or latex, that includes a diaper”) with tubes connecting the diaper to a mask in order to transport the smell of the diaper's waste or flatulence to the wearer's nose. Full definition →
From hose (“flexible tube conveying water or other fluid”, noun) + suit (“a garment or set of garments suitable or required for a given task or activity”, noun), because of the design. Perhaps modelled after diapersuit.
Etymology from Wiktionary, CC BY-SA 4.0.