[callum85]

Those are metaphors and metonyms. MS Word is not a word. MS Office is not an office. Facebook Messenger is literally a thing that carries messages. Apple Watch is literally a watch.

[mmustapic]

Although SQL Server is an SQL server :)

[DonHopkins]

To be fair, MS Word is two letters, a space and a word.

[jonhohle]

Apple Watch is to watches as iPhone is to phones. In both cases they are supersets of what their name suggests, where the consumed set is a tiny fraction of their purpose.