A bear market refers to a market that is in decline. An example could be share/token prices that are continuously dropping, resulting in a continued long-term downward trend.
The most famous example of a bear markets in cryptocurrency and blockchain are the post Mt.Gox bear market which lasted from Early 2014 to late 2016 and the current bear market which started in early 2018.
Bear markets should not be viewed in too much of a negative light as they can provide good opportunities to buy great cryptocurrency coins or tokens at cheap prices.
Bull and Bear markets are part of the natural boom-bust cycle inherent in any market.
In 2017 the Cryptocurrency and Blockchain market grew an amazing 149.37%% from 2016. And even though 2018 has been mostly a bear market, it is still up 3053.40 % from 2016. The fundamentals of investment in cryptocurrency and blockchain have not changed and with growing adoption and awareness the future is bright.
Also see: Bull Market