The Big Dictionary of Dreams

by Martha Clarke
Although it has a long life, it is the tree of cemeteries. Its image has to do with death, but also with eternity. It symbolizes the passage of time, death, and the beginning of perpetual existence. It represents the transition from the physical life (perishable) to the spiritual life that lasts forever. In the Middle Ages, it was considered a sign of welcome. A pilgrim who felt well taken care of in a monastery would plant a cypress at the entrance, so other pilgrims could tell that in that place they would be welcome. Thus, we can say that its symbolism is very complex. 

A Dictionary of Dream Symbols

by Eric Ackroyd
(1) A cypress tree symbolizes death and mourning.

See also Dead / Death.

(2) Being evergreen, however, it also symbolizes immortality; the hope of new life on the other side of death.

See also Dead / Death.

(3) Of course, a cypress may have special significance for you: perhaps, for instance, you associate it with a Mediterranean holiday in which you experienced something meaningful.

Dreamers Dictionary

by Garuda
Symbol: The tree of the righteous, the cypress is a sacred symbol of life, connected to the gods of the underworld.

Vision + Depth Psychology: Seeing a cypress means a sad event or setback at work or at home. Planting a cypress: somebody is going to die.