"Container" means two related but different things nowadays: (1) an abstraction to group some processes and give them their own pid, fs, and network spaces; and

"Container" means two related but different things nowadays: (1) an abstraction to group some processes and give them their own pid, fs, and network spaces; and (2) an archive that contains some application(s) and everything that's required to run them (minus the kernel), plus metadata on what it is and what it requires from the host kernel to actually run.