A graveyard. Quiet. Depressing. Dead people are buried there, never to move. Meanwhile, the living would rather stay away (it's not exactly the kind of place that entices picnickers).
Those factors define a graveyard market as well. It's a market that has seen significant losses over a long period of time. Current investors have lost tons of money (they are the dead and buried). Meanwhile, potential new investors don't want to enter the market, despite the lower prices (they are the living, prefering to picnic somewhere else).