While mining on a NOMP mining pool, I noticed that when you add the confirmed blocks and pending blocks together, they rarely add up to the total blocks found. It is my understanding that the missing blocks were "kicked." What does it mean when a block is "kicked"?
The term seems to have been defined in this GitHub issue: https://github.com/zone117x/node-open-mining-portal/issues/138#issuecomment-42396180.
Kicked basically means orphaned one way or another. Apparently, the creator of this pool software was seeing some strange behavior in the way the daemon would report blocks as being orphaned, and decided to just call them all "kicked" blocks than to differentiate how they were orphaned.
If you are unsure what orphaned blocks are, look at this: What are orphaned and stale blocks?. Essentially they are solved blocks that are not accepted by the network, usually because a different block at the same height was solved at nearly the same time.