membrane

The membrane can be:

generally: a thin elastic membrane or disc
in biology:
a thin membrane with a delimiting or separating function
biological membrane
cytoplasmic membrane
in engineering, physics and chemistry:
selectively permeable membrane for separation of mixtures (e.g. by dialysis, ultrafiltration) and similar purposes, see membrane (chemistry)
in announcement technology: a thin plate (or paper cone) that transmits sound waves on an electrical device in an electroacoustic transducer (e.g. in a microphone or loudspeaker), see diaphragm (sound technology)
diaphragm pump, see under diaphragm pump
diaphragm
in superstring theory etc.: 2-brane, i.e. a special p-brane with two spatial dimensions, see membrane (superstring theory)
in construction: abbreviated: building membrane