1 : formal religious veneration : worship
2 : a system of religious beliefs and ritual; also : its body of adherents
3 : a religion regarded as unorthodox or spurious; also : its body of adherents
5 a : great devotion to a person, idea, object, movement, or work (as a film or book); especially :such devotion regarded as a literary or intellectual fad b : the object of such devotion c : a usually small group of people characterized by such devotion
Generally I don't think most people in America consider Adventism a cult. Walter Martin, famous for his book, "The Kingdom of the Cults" and was the foremost expert in cults, had done a lengthy research into the Seventh-day Adventist church and deemed it "clean."
However, before he died he was rethinking that status. He felt the leaders of the SDA church had not given him all the correct information. He warned Adventists if they continued to see Ellen White as a prophetess, he would have to put them in the cult category.
It is most confusing to label anything a cult because the word has so many different connotations. Many people believe a cult is the same thing as people in the occult. In America the word cult is generally a scary pejorative towards a group. Yet in scholastic circles the first two definitions are used and it simply means a ritualistic religious belief and Christianity is often described as a cult.
Since being out of Adventism, I have run across all different views. When a Southern Baptist Church was trying to get me to join their membership so I could become more actively involved, they insisted that I be rebaptized because the immersion I received into Adventism wasn't a baptism into Christianity. It wasn't a valid baptism. Though they never actually came out and called Adventism the "c" word they certainly acted as if I had been a part of a bizarre, snake handling, Jim Jones group.
Not all felt this way. Many Christians didn't even know what an Adventist was. Many of those I encountered thought Adventists and Jehovah's Witnesses or Mormons were the same thing.
So I don't call Adventism a cult. There is no real communication going on when you use that word unless you really find out what the person believes a cult is.