Definition
Lottery mining refers to solo mining with hardware that has such a small fraction of the network hashrate that finding a block is a very low-probability event, similar to winning a lottery. A Bitaxe producing 500 GH/s against a network of 600+ EH/s has approximately a 1 in 1.2 million chance of finding a block each day.
Despite the low odds, lottery mining appeals to Bitcoin enthusiasts for several reasons: the thrill of the possibility, the philosophical alignment with decentralization, the educational value, and the fact that the full 3.125 BTC reward goes to the finder. The community motto: every hash counts.
In Simple Terms
Solo mining with low odds but full block reward potential. The thrill of the possibility, every hash counts.
Solo mining with low-hashrate devices where finding a block is extremely unlikely but would yield the full block reward. Popular with Bitaxe miners.