The Collaborative International Dictionary of English v.0.48:
Marsh \Marsh\, n. [OE. mersch, AS. mersc, fr. mere lake. See
Mere pool, and cf. Marish, Morass.]
A tract of soft wet land, commonly covered partially or
wholly with water; a fen; a swamp; a morass. [Written also
Marsh asphodel (Bot.), a plant (Nartheeium ossifragum)
with linear equitant leaves, and a raceme of small white
flowers; -- called also bog asphodel.
Marsh cinquefoil (Bot.), a plant (Potentilla palustris)
having purple flowers, and found growing in marshy places;
Marsh elder. (Bot.)
(a) The guelder-rose or cranberry tree (Viburnum Opulus).
(b) In the United States, a composite shrub growing in salt
marshes (Iva frutescens).
Marsh five-finger. (Bot.) See Marsh cinquefoil (above).
Marsh gas. (Chem.) See under Gas.
Marsh grass (Bot.), a genus (Spartina) of coarse grasses
growing in marshes; -- called also cord grass. The tall
Spartina cynosuroides is not good for hay unless cut
very young. The low Spartina juncea is a common
component of salt hay.
Marsh harrier (Zool.), a European hawk or harrier (Circus
aeruginosus); -- called also marsh hawk, moor hawk,
moor buzzard, puttock.
Marsh hawk. (Zool.)
(a) A hawk or harrier (Circus cyaneus), native of both
America and Europe. The adults are bluish slate above,
with a white rump. Called also hen harrier, and mouse
(b) The marsh harrier.
Marsh hen (Zool.), a rail; esp., Rallus elegans of
fresh-water marshes, and Rallus longirostris of
Marsh mallow (Bot.), a plant of the genus Althaea (
Althaea officinalis) common in marshes near the
seashore, and whose root is much used in medicine as a
Marsh marigold. (Bot.) See in the Vocabulary.
Marsh pennywort (Bot.), any plant of the umbelliferous
genus Hydrocotyle; low herbs with roundish leaves,
growing in wet places; -- called also water pennywort.
Marsh quail (Zool.), the meadow lark.
Marsh rosemary (Bot.), a plant of the genus Statice
(Statice Limonium), common in salt marshes. Its root is
powerfully astringent, and is sometimes used in medicine.
Called also sea lavender.
Marsh samphire (Bot.), a plant (Salicornia herbacea)
found along seacoasts. See Glasswort.
Marsh St. John's-wort (Bot.), an American herb (Elodes
Virginica) with small opposite leaves and flesh-colored
Marsh tea. (Bot.). Same as Labrador tea.
Marsh trefoil. (Bot.) Same as Buckbean.
Marsh wren (Zool.), any species of small American wrens of
the genus Cistothorus, and allied genera. They chiefly
inhabit salt marshes.