"Not only is Cassandra’s terminology confusing it’s downright misleading. Row, Column & Key all have existing semantics in the land of databases. To make matters worse, Cassandra’s definitions are not even orthogonal to the existing ones — they exist in a difficult state of quasi-synonymity."

You assumed that the RDB definition of those words was absolute, and didn't bother to question if a different kind of database would use them somewhat differently.