"Consolidation" is a term that is bandied about a lot in recent memory research. Here's my take on what it means.
Becoming a memory
Initially, information is thought to be encoded as patterns of neural activity — cells "talking" to each other. Later, the information is coded in more persistent molecular or structural formats (e.g., the formation of new synapses). It has been assumed that once this occurs, the memory is "fixed" — a permanent, unchanging, representation.