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 "Rank these Names! (Girls)".
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.