The Collaborative International Dictionary of English v.0.48:
Rattlesnake \Rat"tle*snake`\ (r[a^]t"t'l*sn[=a]k`), n. (Zool.)
Any one of several species of venomous American snakes
belonging to the genera Crotalus and Caudisona, or
Sistrurus; sometimes also called rattler. They have a
series of horny interlocking joints at the end of the tail
which make a sharp rattling sound when shaken. The common
rattlesnake of the Northern United States (Crotalus
horridus), and the diamondback rattlesnake (also called
diamondback rattler, and diamondback) of the South and
East (Crotalus adamanteus) and West (Crotalus atrox), are
the best known. See Illust. of Fang.
[1913 Webster +PJC]
Ground rattlesnake (Zool.), a small rattlesnake (Caudisona
miliaria or Sistrurus miliaria) of the Southern United
States, having a small rattle. It has nine large scales on
Rattlesnake fern (Bot.), a common American fern
(Botrychium Virginianum) having a triangular decompound
frond and a long-stalked panicle of spore cases rising
from the middle of the frond.
Rattlesnake grass (Bot.), a handsome American grass
(Glyceria Canadensis) with an ample panicle of rather
large ovate spikelets, each one composed of imbricated
parts and slightly resembling the rattle of the
rattlesnake. Sometimes called quaking grass.
Rattlesnake plantain (Bot.), See under Plantain.
Rattlesnake root (Bot.), a name given to certain American
species of the composite genus Prenanthes (Prenanthes
alba and Prenanthes serpentaria), formerly asserted to
cure the bite of the rattlesnake. Called also lion's
foot, gall of the earth, and white lettuce.
Rattlesnake's master (Bot.)
(a) A species of Agave (Agave Virginica) growing in the
Southern United States.
(b) An umbelliferous plant (Eryngium yuccaefolium) with
large bristly-fringed linear leaves.
(c) A composite plant, the blazing star (Liatris
Rattlesnake weed (Bot.), a plant of the composite genus
Hieracium (Hieracium venosum); -- probably so named
from its spotted leaves. See also Snakeroot.