Excuse me, but are Pink Floyd a rock band, or what? What does "rock music" mean?

For me yes, they are.

Regarding the meaning of rock music, I had opened this topic...

http://www.pianoconcerto.it/forum/index.php?/topic/1452-che-cose-la-musica-rock/

Maybe you will find some useful answers there

very simple, it means 'popular' music, with a more incisive or aggressive aspect, due especially to the use of distorted guitars.... 'pop' (popular) is like rock, without necessarily that more 'aggressive' element.

modern rock was 'born' from blues, the music of Black slaves..... blues has influenced all American popular music. Rock was born in America in the 50s with rock and roll, subsequently popular music in England also absorbed these influences.

Furthermore, the rock guitar, as well as the metal guitar, also comes from the blues guitar, through the use of pentatonic scales for improvisation and the use of 'blue' notes, notes that create peculiar but very expressive dissonances, which in classical music would be defined as 'wrong'.

jazz is the most sophisticated form of blues. I think jazz is also heavily influenced by classical music (Debussy, for example). But all American popular music, including rock, is born from blues.

yes of course Pink Floyd are a 'rock' group....in the album you mention they were more experimental, but always 'rock' and so on. Anyway these are also limiting categories....I don't think Pink Floyd ever thought 'now let's make a rock album' or 'we are a rock group'. The categories have always been imposed by the public or by critics

one must also keep well in mind the so-called "psychedelia"