Chamber of ....Secrets?

[potioncat]

No: HPFGUIDX 185953

I recently watched TMTMNBN--CoS. And, suddenly I wondered, why is 
Slytherin's hidden chamber called the Chamber of Secrets? All that was 
there was a big snake. I mean, that was enough. 

But why "secrets"? Why not The Monstor's Lair; The Horrible Chamber: 
The Hidden Menace? Even the legend (although I may not be firm on the 
canon) was that there was a monster in the chamber--not that there were 
hidden secrets. So why did wizards or JKR call it the Chamber of 
Secrets? Does anyone have any ideas on this?

Potioncat, who thinks the real Chamber of Secrets was DD's office.