From the Greek:
Sorry, agnostic container? I searched some stuff on google, but there was nothing specific. Is this a some sort of a library, or just a spontaneous word you made?
a - negating prefix
gnosis - 'knowledge'
Agnostic essentially means 'without knowledge'.
When something in programming terms is described as agnostic it usually means that it doesn't care about something relevant to the subject. In this case it would be a container that doesn't care about the position of the objects it stores. If something is described as type agnostic that means it doesn't care about type, etc. I think the most common use I've heard of it in programming is 'platform agnostic', which describes something that is compatible with any platform because it doesn't need any information about the platform in order to run. For instance, the TCP/IP suite is platform agnostic. It runs the same on a mac, a PC or a playstation.