The name Lilliana is a girl's name meaning "lily, a flower". Lilliana is ranked #290 on our popularity charts and is often added to lists like Girl Baby Names Moving Up Fast and discussed in our forums with posts like "If I had 8 daughters whose names started with...".
From the experts:
While Lillian is the English version of this elaborated flower name and Liliana is the authentic Spanish or Portuguese spelling that's pronounced the same, Lilliana is a hybrid spelling that doesn't exactly have its own ethnic origin but that can be considered perfectly proper nonetheless. However you configure it, it's a lovely name and if it looks more appealing to you with three L's versus two, go for it.