What is the definition of the Fluid Mosaic Model?

Simply put, the fluid mosaic model is a description of the membrane of a cell. The fluid part refers to the phospholipids of a cell membrane, which, like liquid, flow. The mosaic part refers to proteins embedded in the phospholipid bilayer that act as conduits through which molecules enter and exit the cell.

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The currently accepted model of cell membrane structure, which envisions the membrane as a mosaic of individually inserted protein molecules drifting laterally in a fluid bilayer of phospholipids.

Fluid mosaic is a term used to describe the current model of the cell membrane.

Cell membranes are basically double layers (bilayers) of molecules called phospholipids. 'Floating' in the phospholipid bilayer are molecules of protein. a mosaic is a structure made up of many different parts. Viewed from above the membrane would look something like a mosaic - a 'sea' of lipid with many 'islands' of protein.

The lipid bilayer is not rigid, and the lipid and protein molecules are able to move sideways in the membrane i.e. the membrane is fluid.

This model of the cell membrane was proposed by Singer and Nicolson in 1972, and has been supported by many experiments since then.
model for cell membrane given by SJ singer and GL Nicholoson