It should be noted that the name of the book probably comes from a transcription error.

At the end of the book, the narrator writes: "Stat rosa pristina nomine, nomina nuda tenemus", which means : "The ancient Rose remains by its name, naked names (are all that) we have". As it stands, this sentence can be seen as a hint at the relationship between the thing and the word, between the remanent sign and the transient signified - an appealing conclusion for a semiologist such as Eco.

However, this verse comes from the poem De contemptu mundi ("On the Contempt of the World"), written by Bernard of Cluny (aka Bernard of Morlay). This poem is mainly a satire against the moral corruption of the world in general (and of the Catholic Church in particular) in the 12th century. Among other things, this long poem (3000 verses) stresses the transitory nature of this world's pleasures and glories, and uses the great cities of the past (Babylone, Rome) as an example. The most coherent reading for the verse that Eco cites is actually : "Stat ROMA pristina nomine", etc. Here is the context:
    Nunc ubi Regulus aut ubi Romulus aut ubi Remus?
    Stat ROMA pristina nomine, nomina nuda tenemus
"Where is Regulus now, and where is Romulus, and where is Remus ? The antique Rome only remains through its name, empty names are all that we hold".

The Name of the Rose is a masterpiece of contemporary literature. I tend to think that this misreading makes this mysterious, evocative title even more poetic. Of course, ymmv.