What does the word "Star" in "Star Wars" refer to?

In case it's not clear, a star (in this context) is:

1. Any small luminous dot appearing in the cloudless portion of the night sky, especially with a fixed location relative to other such dots.
2. (astronomy) A luminous celestial body, made up of plasma (particularly hydrogen and helium) and having a spherical shape. Depending on context the sun may or may not be included.

^{Source: Wiktionary}

The literal meaning of the title could be interpreted as "A series of wars among the stars". "Among the stars" is a turn of phrase used to mean "out in space".

Compare with the title Star Trek, which means "a journey (trek) among the stars".

Also compare with the TV show Star Search, which means "a search for stars". In this case, "stars" means people who will become famous, not large balls of hydrogen fusion in space, but the grammar of the title is the same.

In general, an English construction of noun verb often means, "doing verb in the context of noun". For example, sea trade is the trading of goods using ocean vessels. Shore leave means "a break from service that takes place on dry land (not at sea)". Space walk means "an excursion from a spacecraft wearing only a spacesuit or EVA suit" - in other words, "a walk in space".

If that doesn't clarify things enough, you might want to ask your question on the English Language & Usage Stack Exchange.

While Todd Wilcox' answer is true in the literal sense that Star Wars refers to the wars happening across the galaxy on planets and in outer space, it also refers to both a metaphorical (prominent heroes and villains) and metaphysical (power coming from elsewhere) definition.

Star Wars is an American epic space-opera media franchise created by George Lucas. The franchise began with the eponymous 1977 film and quickly became a worldwide pop-culture phenomenon.

Star Wars, especially the Skywalker family Saga (Epsiodes I-IX) is about "iconic" Heroes and Villains who are featured in this particular story, as the story itself asks, what does "legacy" mean? What information can we pass on?

Epic films are a style of film-making with large scale, sweeping scope, and spectacle. The usage of the term has shifted over time, sometimes designating a film genre and at other times simply synonymous with big-budget filmmaking. Like epics in the classical literary sense it is often focused on a heroic character. An epic's ambitious nature helps to set it apart from other types of film such as the period piece or adventure film.

To expound on that, because the work is also a "Fantasy Epic", there is also a metaphysical energy, The Force, that is believed to connect all life together, but some are born "Force Sensitive" and can tap into this energy and kinetically use it.

Star Wars features elements such as knighthood, chivalry, and archetypes related to the fantasy genre. The Star Wars galaxy, unlike science fiction that features sleek and futuristic settings, is portrayed as dirty and grimy in Lucas's concept of a "used future". Lucas made a conscious effort to parallel scenes and dialogue between films, and especially the journey of Anakin Skywalker in the prequels with that of his son Luke. He has collectively referred to the first six episodic films as "the tragedy of Darth Vader," and said that the theme of the saga is redemption.[196]

The final scene in The Last Jedi depicts servant children playing with a toy of Luke Skywalker, and one boy using the Force to grab a broom. According to Inverse, this symbolizes that "the Force can be found in people with humble beginnings."

In the first two trilogies of the Skywalker Saga the general tenor of 'good vs evil' comes from light side and dark side "force users" referred to as the Jedi and Sith. The first trilogy sees the rise and fall of Anakin Skywalker that is echoed in the downfall of the Republic and the Jedi Order, juxtaposing the rise of The Empire and birth of Darth Vader through the Sith Lord, Darth Sidious or Emperor Palpatine.

In the next trilogy the twin children of the Anakin Skywalker must attempt to restore order to the galaxy, as Anakin's son Luke learns the ways of the fallen Jedi in order to confront his father, whose now a destructive Sith Lord.

EMPIRE - Rian Johnson Interview

"He's taken himself out of the fight, he's sitting on that island in exile. I know the Luke I grew up with is not a coward, he's not sitting out there hiding, so I had to come up with a reason he was there that was active and positive, and something I could genuinely believe I could think in his shoes," says Johnson. "And the thing that came to me that seemed to make sense to me is this notion that he seems this hero worship of him and of the Jedi that is detrimental to the galaxy. The universe has put its faith in its false god of the Jedi and they need to forget the religion so they can get back to god, that light can rise from a worthier source. And because he's the last Jedi and a symbol of that, it then becomes this self-sacrifice he has to do to take himself out of it when he knows his friends are dying, when he knows the thing he'd like to do is get back in the fight. He's taken the weight of the world on his shoulders by taking himself out of the equation so that the Jedi can die out. The end of the movie is him embracing the part of the past that the present needs, which right now is the legend of Luke Skywalker, they need something to believe in, they need that action figure of Luke Skywalker to grab on to, that inspiration to stare up at the stars and believe that you can be a hero."

"I wanted Luke's death to be peaceful, to be on his terms I wanted it to be a victory. I wanted it to be that he's done this huge grand act that has restored the spark of hope to the galaxy. I'm hesitant to put into words what he does in the end, but it is completed."

In the last trilogy, the Republic was restored, but fell pray to the Empire turning into the New Order, where Darth Vader's grandson, who claims not to be Sith, eventually comes to power leaning into the dark side. But it is his Uncle, Luke Skywalker's legacy and his possible feelings for an outsider named Rey, that threatens the success of The New Order quashing the resistance once and for all, but Luke sacrifices himself and stories about his bravery and honor are spread across the galaxy inspiring a whole new generation of people to join nearly defeated resistance, aka the "Spark of Hope"! (We have to wait and see how the last episode plays out to know more.)

"May the Force be With You."

In addition, through out these works and in other works, including Star Wars Rebels, the notion of what The Force is and how one should use it (methodology/applied philosophy) is debated, but in many cases there is evidence that the Force does in fact exist and have a "will" and therefor there is an additional mysterious element of fate at work (some Force Users may be able to see the future), which gives Star Wars philosophical and/or spiritual meaning, as the Force is coming from within and beyond the self; a metaphorical definition playing on "stars" as in information coming from somewhere else, like from "God" or the "The Heavens"...