This is the 5054th most frequent Catalan word.
alexandre
"Alexandre" in Catalan is the equivalent of "Alexander," a proper noun used as a male given name.
Here, 'Alexandre' serves as a proper noun, denoting a person's name, and acts as the subject of the sentence.
L'Alexandre va comprar un llibre interessant.
Alexandre bought an interesting book.
In this case, 'Alexandre' continues to act as a proper noun, referring to a person's name, but here it is used as part of the predicate to indicate authorship by a named individual.
El poema va ser escrit per un tal Alexandre.
The poem was written by someone named Alexandre.
Here, 'Alexandre' is still a proper noun used as a name, while it appends the profession to give context to the person's identity in the sentence.