tetra-, tetr-

(Greek: four; a number used as a prefix)

tetrarchy
tetrarchy, tetradarchy
A government by four persons jointly; a set of four tetrarchs or rulers; a country divided into four petty governments.
tetraschistic
tetraselenodont
Having four crescentic ridges on molar teeth.
tetrasome
tetrasomic
tetrastich
A stanza, epigram, or poem, consisting of four verses or lines.
tetrastichiasis
Duplication of the growth of the eyelashes (in four rows).
tetrathecal
Having four loculaments (cell of a pericarp in which the seed is lodged), or thecae: a case, covering, or sheath; such as, the pollen sac of an anther, the spore case of a moss, or the outer covering of the pupa of certain insects.
tetratheism (s) (noun)
A religious belief that in the Godhead there are, in addition to the Divine Essence, three other persons; the Father, the Son, and the Holy Spirit; and so making in the Godhead three and one instead of three in one.
tetratomic
tetravalence
tetravalent
tetrode
tetrodotoxin, tetraodontoxin, spheroidin
1. A highly lethal neurotoxin present in numerous species of puffer fish and in certain newts (in which it is called tarichatoxin).

Ingestion rapidly causes malaise, dizziness, and tingling around the mouth, which may be followed by ataxia, convulsions, respiratory paralysis, and death.

2. A potent neurotoxin found in the liver, skin, and ovaries of the puffer fish, and in the California newt.
3. A powerful nerve poison found in the eggs of the California newt and in certain puffer fish in Japan.

In concentrated form, it is more toxic than cyanide.

About 100-200 people become ill each year after eating fugu, or pufferfish each year. Roughly half of these intoxifications are fatal, even with immediate treatment.
—Dr. Chein-Yuan Kao, Brooklyn Medical Center.

You can find more information about tetrodotoxin here.

Cross references of word families that are related, partially or totally, to: "four, fourth": quadri-; quatr-; tessara-.