semipermeable
adjective chemistry specialized uk/ˌsem.iˈpɜː.mi.ə.bəl/ us/ˌsem.iˈpɝː.mi.ə.bəl/
（细胞膜等）半渗透性的，半可透性的
Something, for example a cell membrane, that is semipermeable allows some liquids and gases to pass through it, but not others.