What does SPIDER mean?

noun

1. predatory arachnid with eight legs, two poison fangs, two feelers, and usually two silk-spinning organs at the back end of the body; they spin silk to make cocoons for eggs or traps for prey
2. a computer program that prowls the internet looking for publicly accessible resources that can be added to a database; the database can then be searched with a search engine
3. a skillet made of cast iron