Speaking as a 'informático', I usually refer to it as MS Word. Note, also, that it is customary to capitalize the first letter. That can serve to differentiate between Word the software and 'word' the word :)
On the topic, that isn't even the worst of the names that Microsoft uses. There are two different things that Microsoft makes that are called 'Project' - one a type of database file and another a software for project management. Neither should have that name as it causes confusion, and they also get confused with each other. It can be a real nuisance.