I'll source the Bitcoin Wiki for the definition of mining,
https://en.bitcoin.it/wiki/Mining. The very first sentance of the page states:
Mining is the process of adding transaction records to Bitcoin's public ledger of past transactions.
Here's a few other mining definitions (emphasis added by me):
https://bitcoin.org/en/faq#what-is-bitcoin-miningMining is the process of spending computing power to process transactions, secure the network, and keep everyone in the system synchronized together.
Mining software listens for transactions broadcast through the peer-to-peer network and performs appropriate tasks to process and confirm these transactions.
http://www.investopedia.com/terms/b/bitcoin-mining.aspBitcoin mining is the process by which transactions are verified and added to the public ledger, known as the block chain, and also the means through which new bitcoin are released.
http://whatis.techtarget.com/definition/Bitcoin-miningBitcoin mining is the processing of transactions in the digital currency system, in which the records of current Bitcoin transactions, known as a blocks, are added to the record of past transactions, known as the block chain.
http://en.wikipedia.org/wiki/Bitcoin#MiningMining is a record-keeping service.[note 9] Miners keep the block chain consistent, complete, and unalterable by repeatedly verifying and collecting newly broadcast transactions into a new group of transactions called a block.
Therefore, I contend that if you're not adding transactions to the blockchain (i.e. solving an empty block) then you are not mining.