From the "Standard Terms" section of our Dictionary of Semenyms:

spermium - sperm; a clinical term used to suggest the fertility of semen. “When a man is about to shoot off, all I can think of is getting that hot spermium in my mouth. I hate to see even a drop go to waste. I’ve even licked a hot puddle off the floor once, during a get-together with a couple of buddies that got out of hand. Tony said it was sort of disgusting, but he watched me lick it all up and he stroked off while I was doing it!” —Joey W.