Not exactly.

Security through obscurity in cryptosystems would mean defining your own crypto algorithm (or using a secretly-defined one, secret in the sense that it is unknown to the adversaries) to protect your system.

It is NOT bad in itself. It IS bad if you only rely on that. Even if you'd use a "secret" algorithm, you MUST protect the keys as with a public algorithm. Also, being secret means you cannot benefit from the cryptanalysis of the community, which is in practice very important. BUT... if you have a lot of cryptanalysis expertise at disposal, then using a secret algorithm can be very effective.