The Collaborative International Dictionary of English v.0.48:
Poison \Poi"son\, n. [F. poison, in Old French also, a potion,
fr. L. potio a drink, draught, potion, a poisonous draught,
fr. potare to drink. See Potable, and cf. Potion.]
1. Any agent which, when introduced into the animal organism,
is capable of producing a morbid, noxious, or deadly
effect upon it; as, morphine is a deadly poison; the
poison of pestilential diseases.
2. That which taints or destroys moral purity or health; as,
the poison of evil example; the poison of sin.
Poison ash. (Bot.)
(a) A tree of the genus Amyris (Amyris balsamifera)
found in the West Indies, from the trunk of which a
black liquor distills, supposed to have poisonous
(b) The poison sumac (Rhus venenata). [U. S.]
Poison dogwood (Bot.), poison sumac.
Poison fang (Zool.), one of the superior maxillary teeth of
some species of serpents, which, besides having the cavity
for the pulp, is either perforated or grooved by a
longitudinal canal, at the lower end of which the duct of
the poison gland terminates. See Illust. under Fang.
Poison gland (Biol.), a gland, in animals or plants, which
secretes an acrid or venomous matter, that is conveyed
along an organ capable of inflicting a wound.
Poison hemlock (Bot.), a poisonous umbelliferous plant
(Conium maculatum). See Hemlock.
Poison ivy (Bot.), a poisonous climbing plant (formerly
Rhus Toxicodendron, or Rhus radicans, now classified
as Toxicodendron radicans) of North America. It is
common as a climbing vine, especially found on tree
trunks, or walls, or as a low, spreading vine or as a
shrub. As a low vine it grows well in lightly shaded
areas, recognizable by growing in clusters of three
leaves. Its leaves are trifoliate, rhombic-ovate, and
variously notched. Its form varies slightly from location
to location, leading to some speculation that it may
consist of more than one species. Many people are poisoned
by it, though some appear resistant to its effects.
Touching the leaves may leave a residue of an oil on the
skin, and if not washed off quickly, sensitive areas of
skin become reddened and develop multiple small blisters,
lasting for several days to several weeks, and causing a
persistent itch. The toxic reaction is due to an oil,
present in all parts of the plant except the pollen,
called urushiol, the active component of which is the
compound pentadecylacatechol (according to [a
H. Booras). See Poison sumac. It is related to poison
oak, and is also called mercury.
Poison nut. (Bot.)
(a) Nux vomica.
(b) The tree which yields this seed (Strychnos
Nuxvomica). It is found on the Malabar and Coromandel
Poison oak (Bot.), a dermatitis-producing plant often
lumped together with the poison ivy (Toxicodendron
radicans) in common terminology, but more properly
distinguished as the more shrubby Toxicodendron
quercifolium (syn. Toxicodendron diversilobum), common
in California and Oregon. Opinion varies as to whether the
poison oak and poison ivy are only variants of a single
species. See poison ivy, above.
Poison sac. (Zool.) Same as Poison gland, above. See
Illust. under Fang.
Poison sumac (Bot.), a poisonous shrub formerly considered
to be of the genus Rhus (Rhus venenata), but now
classified as Toxicodendron vernix; -- also called
poison ash, poison dogwood, and poison elder. It has
pinnate leaves on graceful and slender common petioles,
and usually grows in swampy places. Both this plant and
the poison ivy (Toxicodendron radicans, formerly Rhus
Toxicodendron) have clusters of smooth greenish white
berries, while the red-fruited species of this genus are
harmless. The tree (Rhus vernicifera) which yields the
celebrated Japan lacquer is almost identical with the
poison sumac, and is also very poisonous. The juice of the
poison sumac also forms a lacquer similar to that of
[1913 Webster +PJC]
Syn: Venom; virus; bane; pest; malignity.
Usage: Poison, Venom. Poison usually denotes something
received into the system by the mouth, breath, etc.
Venom is something discharged from animals and
received by means of a wound, as by the bite or sting
of serpents, scorpions, etc. Hence, venom specifically
implies some malignity of nature or purpose.