The Collaborative International Dictionary of English v.0.48:

Cypress \Cy"press\ (s?"pr?s), n.; pl. Cypresses (-?z). [OE.
   cipres, cipresse, OF. cipres, F. cypr?s, L. cupressus,
   cyparissus (cf. the usual Lat. form cupressus), fr. Gr. ????,
   perh. of Semitic origin; cf. Heb. g?pher, Gen. vi. 14.] (Bot)
   A coniferous tree of the genus Cupressus. The species are
   mostly evergreen, and have wood remarkable for its
   durability.
   [1913 Webster]

   Note: Among the trees called cypress are the common Oriental
         cypress, Cupressus sempervirens, the evergreen
         American cypress, Cupressus thyoides (now called
         Chamaecyparis sphaeroidea), and the deciduous
         American cypress, Taxodium distichum. As having
         anciently been used at funerals, and to adorn tombs,
         the Oriental species is an emblem of mourning and
         sadness.
         [1913 Webster]

   Cypress vine (Bot.), a climbing plant with red or white
      flowers (Ipot[oe]a Quamoclit, formerly Quamoclit
      vulgaris).
      [1913 Webster]

WordNet (r) 3.0 (2006):

Taxodium distichum
    n 1: common cypress of southeastern United States having trunk
         expanded at base; found in coastal swamps and flooding
         river bottoms [syn: bald cypress, swamp cypress, pond
         bald cypress, southern cypress, Taxodium distichum]