I'm not 100% sure what you mean by this but usually star systems are classed as single (Just one star), binary (meaning two stars orbiting each other), triple (three stars orbiting each other), etc... As our Sun is the only star in this system it is a single star system and therefore none of the others.
A binary star system.
No, the sun is not part of a multiple star system, except to the extent that it is one of the many stars in the Milky Way Galaxy.
the sun is the only star in our solar system. It is close to us, relatively speaking, so looks bigger. Other stars you see belong to other solar systems.
The Sun in itself is a star, but Proxima Centauri is the closest star to our solar system at a distance of about 4.2421 light years.
the sun is. It is also the ONLY star in THIS solar system.
According to their system of classification, the Sun is known as a yellow dwarf star. This group of stars are relatively small, containing between 80% and 100% the mass of the Sun. So the Sun is at the higher end of this group. The official designation is as a G V star- http://www.universetoday.com/guide-to-space/the-sun/what-kind-of-star-is-the-sun/
Our sun is actually a small star, tons of stars are way bigger than our sun. One. Each star is a sun.
That would be difficult to explain. -- The Sun IS a star. -- It IS in my solar system. -- It's the ONLY star in my solar system. -- So the sun is THE star in my solar system.
class G
medium-sized star.
A star found in our solar system is the Sun. The Sun is a star.
The only star in the solar system is the sun.