polyvinylpyrrolidone

noun

poly·​vi·​nyl·​pyr·​rol·​i·​done -ˌvīn-ᵊl-pi-ˈräl-ə-ˌdōn 

: a water-soluble chemically inert solid polymer (−CH₂CHC₄H₆NO−)_n used chiefly in medicine as a vehicle for drugs (as iodine) and especially formerly as a plasma expander

called also povidone