2001: A Space Odyssey sneaks an allusion into its title. The Odyssey is a long Greek poem by Homer about a dude named Odysseus who goes on a long voyage. So what's up with the title is that Clarke is saying, that old Greek dude went on a long voyage and had adventures way back when, and so here's a story about the future of 2001, when some other dude is going to go on an awesome voyage also.
Shmoop would like to be able to tell you there's more to it than that, but there doesn't actually seem to be. James Joyce wove incredibly complex parallels and allusions to the Odyssey throughout his novel Ulysses, but Arthur C. Clarke ain't that kind of modernist literary monolith. Space Odyssey here just means "cool space voyage." If you don't like it, argue with the intergalactic star baby.