No the opposite of alive is dead, there can't be 2 different things that have the same opposite, if what you say is true then what is the opposite of dead? undead or alive???
Zombie vs Human
"Stop. Who are you, what are you doing here!"
"Hold your fire. I'm a human."
"Woooo. Sorry about that, I thought you were one of them"
"What's going on in this town?!"
"I don't have a clue, by the time I noticed something was wrong, the entire city was infested with zombies!"
Thus, the "undead" has synonyms such as "zombie" and "one of them".
However; human is the non corpsified version of the "undead".
Both walk around.