Single Mode cable is a single stand (most applications use 2 fibers) of glass fiber with a diameter of 8.3 to 10 microns that has one mode of transmission. Single Mode Fiber with a relatively narrow diameter, through which only one mode will propagate typically 1310 or 1550nm. Carries higher bandwidth than multimode fiber, but requires a light source with a narrow spectral width. Synonyms mono-mode optical fiber, single-mode fiber, single-mode optical waveguide, uni-mode fiber.

mode means path, the way in which light travel, in the fiber means angle in multi mode fiber light can travel in more then one angle so it is called multi mode fiber.

but in single mode fiber there is dedicated path or single path through which light beam/source can travel.

Multimode fiber (MMF.

Yes, it can. But it requires a special converter - single to multi-mode.

Every single mode can act as a multi mode fiber for light having shorter wavelengths than the one it is designed to be single mode for.