The defintion of star/planetary/solar system In many science fiction stories, we hear the term star system that mostly refers to a star and its planets. This is often used interchangeably with the term solar system. But after some research I understand this:

Planetary system refers specifically to anything orbiting a star that is not a star itself. According to Wikipedia, this generally refers to the planets, but may include other objects like asteroids and dwarf planets. It does not refer to the star itself.

Star system refers to any system with two (binary) or more (multiple) stars, but only the stars themselves, not planets or anything else.

Solar system generally refers to our own Solar system but there are situations where "solar system" (lowercase) refers to a star and the planets or other objects orbiting it (as long as something orbits the star).

So, is it incorrect to use the term solar system/star system to refer to a star and its planets?
I think it's largely a matter of personal preference. Some people will want you to be technically correct and only use "solar system" to refer to the Sun and the objects that are under its gravitational influence. Wikipedia defines it as such:


  The Solar System comprises the Sun and the objects that orbit it, whether they orbit it directly or by orbiting other objects that orbit it directly.


NASA says that the term is more general:


  A solar system refers to a star and all the objects that travel in orbit around it. Our solar system consists of the sun - our star - eight planets and their natural satellites (such as our moon); dwarf planets; asteroids and comets.


As an astronomy enthusiast, I do differentiate between "stellar system"/"star system" and "planetary system". I'd use "planetary system" to refer solely to the planets in a system, as well as their moons, while I'd use "stellar system" to refer to the whole thing. That's just my opinion, though, and I'm unsure what professionals use. In casual conversation (especially with a non-expert), you can probably use whatever term you want. If you're using it formally, you should probably do some more research. And while you're at it, check whether or not you should capitalize "Solar" and "System" in "Solar/solar System/system". If people nag you about terminology, they'll nag you about capitalization.