What Do The Vampire Characters Mean By "Offspring"?

As the title suggests, I have a question about what the term "offspring" means in Call of the Night. I haven't read the manga or anything, but got into the series recently via the anime, which I finished last night. The show was fantastic, and season 2 was awesome. However, a question that I've had since episode 1 was what offspring meant in the context of the series and blood-sucking. At first, I thought that it was literally offspring—by biting someone, they can create children; however, the term also seems to mean turning someone into their offspring, which made no sense to me. So I was hoping someone could clear it up for me, since it doesn't seem to be literal—why "offspring"? Why not some other word?

Thanks!