hmmm, sorry but that piggy just doesn't fly
A mere subpresence should not, and is not elevated above its core subject matter. It is a horror film. It's a traditional monster flick (originally intended as a Coreman movie in fact); in space (like most of his shit horror films). It's therefore a horror film set in a scifi environment. A so called scifright.
But I don't get what your trying to get at saying its a scifi, therefore it can't be a horror film. You just failed boolean logic
he likes football, he likes cricket;
he likes football therefore he does not like cricket = 0
To quote Spock, "it is illogical jim"
Horror film, in space. Your dictionary quotes are also flawed in the fact that one is describing merely a genre, whilst the other is taking a literal and applicable version of horror rather than its genre descriptive equivalent
But this arguement has been done to death on horror has a home (quite a nice thread if you want to dig it up) previously and as a case to allow horror movies to be posted here, I already said I don't mind since we split the database, so its irrelevant (despite the fact that to call alien a scifi movie
over a horror movie is just negating what the movie is in my opinion) as an arguement for allowing their postage here. If you want to chat about it, pick up on where the alien discussion left off @ forum.dead-donkey.com . (It was primarily about Alien 3, the other one I'd describe as a 'horror' movie, as Aliens is a Sci-fi/action and ditto on number 4).