The word bitcoin first occurred and was defined in the white paper that was published on 31 October 2008. It is a compound of the words bit and coin. The white paper frequently uses the shorter coin.
There is no uniform convention for bitcoin capitalization. Some sources use Bitcoin, capitalized, to refer to the technology and network and bitcoin, lowercase, to refer to the unit of account. The Wall Street Journal, The Chronicle of Higher Education, and the Oxford English Dictionary advocate use of lowercase bitcoin in all cases, a convention which this article follows.
The unit of account of the bitcoin system is bitcoin. As of 2014, tickers used to represent bitcoin are BTC and XBT. Small amounts of bitcoin used as alternative units are millibitcoin (mBTC) and satoshi. Named in homage to bitcoin’s creator, a satoshi is the smallest amount within bitcoin representing 0.00000001 bitcoin, one hundred millionth of a bitcoin. A millibitcoin equals to 0.001 bitcoin, one thousandth of a bitcoin.