membrane

mem·brane

noun \ˈmem-ˌbrān\

Definition of MEMBRANE

1

: a thin soft pliable sheet or layer especially of animal or plant origin

2

: a piece of parchment forming part of a roll

— mem·braned \ˈmem-ˌbrānd\ adjective

Origin of MEMBRANE

Middle English, from Latin membrana skin, parchment, from membrum

First Known Use: 15th century

mem·brane

noun \ˈmem-ˌbrān\   (Medical Dictionary)

Medical Definition of MEMBRANE

1

: a thin soft pliable sheet or layer especially of animal or plant origin

2

: a limiting protoplasmic surface or interface—see nuclear membrane, plasma membrane

—mem·braned \ˈmem-ˌbrānd\ (audio pronunciation) adjective

membrane

noun    (Concise Encyclopedia)

In biology, the thin layer that forms the outer boundary of a living cell or of an internal cell compartment. The outer boundary is the plasma membrane, and the compartments enclosed by internal membranes are called organelles. Biological membranes have a dual function: separation of vital but incompatible metabolic processes conducted in the organelles; and passage of nutrients, wastes, and metabolic products between organelles and between the cell and the outside environment. Membranes consist largely of a double layer of lipids in which are embedded large proteins, many of which transport ions and water-soluble molecules across the membrane. See also cytoplasm, eukaryote.