tetrad /tetˈrad/ noun

1. A group of four
2. An atom, radical or element having a combining power of four (chem)

tetˈrad or tetradˈic adjective

tetradactyl /-dakˈtil/ adjective (Gr daktylos digit; zoology)

1. Four-fingered
2. Four-toed

noun

A four-toed animal

tetradacˈtylous adjective

Having four fingers or toes

tetradacˈtyly noun

The condition of being tetradactylous

tetˈradite noun

1. A person who attaches mystic properties to the number four
2. A believer in a godhead of four persons

tetˈradrachm /-dram/ noun

An ancient Greek coin worth four drachmas

tetradymite /ti-tradˈi-mīt/ noun

(Gr tetradymos fourfold) a grey metallic mineral, an ore of tellurium, Bi₂Te₂S

Tetradynamia /-di-nāˈmi-ə/ plural noun

(in Linnaeus's system) a class corresponding to the Cruciferae

tetradynamous /-dinˈə-məs/ adjective

(Gr dynamis power) having four long stamens in pairs and two short, as in the Cruciferae

tetraethyl /-ēthˈīl, -eˈthil/ adjective

Having four ethyl groups, as tetraethyl lead or lead tetraethyl, Pb(C₂H₅)₄, a compound formerly added to petrol as an antiknock agent

tetrafluoroethˈylene noun

A dense colourless gas that is polymerized to make polytetrafluoroethylene

tetˈragon /-gən, -gon/ noun

(see -gon) a plane figure of four angles and four sides

tetragonal /-ragˈə-nəl/ adjective

1. Having the form of a tetragon
2. Referable to three axes at right angles, two of them equal (crystallography)

tetragˈonally adverb

tetragˈonous adjective (botany)

With four angles and convex faces

tetˈragram /-gram/ noun

1. (Gr gramma a letter) a word or inscription of four letters
2. (also with cap) the tetragrammaton
3. A (complete) quadrilateral (geometry)

tetragrammˈaton noun

1. (also with cap) vocalized as the name YaHWeH, JeHoVaH, etc, as written with four Hebrew letters, regarded as a mystic symbol
2. Any other sacred word of four letters, as the Latin Deus

Tetragynia /-jinˈi-ə/ plural noun

(see gyn-) (in the Linnaean system) an order of plants (in various classes) with four pistils

tetragynˈian or tetragynous /-rajˈi-nəs/ adjective

tetrahēˈdral adjective

Of, relating to, like or in the form of a tetrahedron

tetrahēˈdrally adverb

tetrahēˈdrite noun

Grey copper ore, sulphide of copper and antimony often occurring in tetrahedral crystals

tetrahedron /-hēˈdrən/ noun (pl tetrahēˈdrons or tetrahēdra /-drə/)

1. (Gr hedrā a base) a solid figure or body with four plane faces
2. (in full, regular tetrahedron) a tetrahedron whose surfaces are equilateral triangles

tetrahydrocannˈabinol noun

The main intoxicant substance in marijuana

tetrahydrofōˈlate noun

Folic acid, vitamin B₇

tetrahydrogestrinone /-jestˈri-nōn/ noun

A synthetic steroid, illegally used as a performance-enhancing drug by some athletes (abbrev THG)

tetrakishexahēˈdron noun

(Gr tetrakis four times) a figure formed by erecting equal pyramids on all the faces of a cube

tetralˈogy noun

1. (Gr tetralogiā) (in ancient Greece) a group of four dramas, usu three tragic and one satyric
2. Any series of four related dramatic or operatic works or stories

tetramˈeral adjective

Four-parted

tetramˈerism noun

Division into four parts

tetramˈerous adjective

(Gr meros part) having four parts, or parts in fours

tetrameter /ti-tramˈi-tər/ noun

(Gr metron measure) a line of a verse of four measures (dipodies or feet)

Tetˈramorph noun

A pictorial representation of the symbolic attributes of the four evangelists combined in a single figure

tetramorˈphic adjective

(see morphic) having four forms

Tetranˈdria plural noun

(in Linnaeus's classification) a class of plants with four stamens

tetranˈdrian adjective

tetranˈdrous adjective

(Gr anēr, andros man; in the sense of male) having four stamens

tetrapla /tetˈrə-plə/ noun

(Gr neuter pl of tetraploos fourfold) an edition of four parallel texts, esp Origen's of the Old Testament

tetraplēˈgia noun

Quadriplegia

tetraplēˈgic adjective

tetraploid /tetˈrə-ploid/ adjective

(Gr tetraploos fourfold, and eidos form) of cells, nuclei or organisms, having four times the haploid (twice the normal) number of chromosomes

noun

A tetraploid organism, cell or nucleus

tetˈraploidy noun

The condition of being tetraploid

tetˈrapod /-pod/ noun

1. (Gr tetrapous four-footed, from pous, podos foot) a four-footed animal
2. Any vertebrate above the fishes
3. A reinforced-concrete block laid against a sea wall to break the force of the waves
4. A structure with four supporting arms at 120º to each other radiating from a central point, three arms supporting the structure at any one time, with the fourth vertical

adjective

(of an animal or structure) having four feet

tetrapodˈic adjective

(of verse) having four metrical feet

tetrapodous /-trapˈ/ adjective

tetrapˈody noun

A group of four metrical feet

tetrapolis /ti-trapˈo-lis/ noun

(Gr polis a city) a group of four towns

tetrapolˈitan adjective

(Tetrapolitan Confession the Confession which the four cities of Strasburg, Constance, Memmingen and Lindau presented to the Diet of Augsburg (11 July 1530), and, properly speaking, the first Confession of the Reformed Church)

tetrapˈteran /-rən/ or tetrapˈterous adjective

(see -pteran, -pterous under ptero-) four-winged

tetraptote /tetˈrap-tōt/ noun

(Gr ptōsis a case) a noun with only four cases

tetrarch /tetˈrärk or tēˈträrk/ noun (Gr archē rule, origin; historical)

1. Under the Romans, the ruler of the fourth part of a province
2. A subordinate prince
3. The commander of a subdivision of a Greek phalanx
4. One of four joint rulers

adjective (botany; also tetrarchˈical)

Having four xylem strands

tetrarchˈic adjective

tetˈrarchy noun

1. The office, rank, period of office or jurisdiction of a tetrarch
2. The fourth part of a province (also tetˈrarchate)
3. The condition of being tetrarch (botany)

tetrasemic /-sēˈmik/ adjective (Gr sēma a sign; prosody)

Equivalent to four short syllables, as is a dactyl, anapaest or spondee

tetrasporangium /-spə-ranˈji-əm/ noun

The sporangium in which tetraspores are formed

tetˈraspore /-spōr, -spör/ noun

(Gr sporā seed) an asexual spore formed in groups of four in red seaweeds

tetrasporic /-sporˈik/ or tetrasporous /ti-trasˈpə-rəs or tet-rə-spōˈrəs, -spöˈ/ adjective

tetˈrastich /-stik/ noun

(Gr stichos a row) a stanza or set of four lines

tetrastichal /ti-trasˈti-kl/ or tetrastichic /tet-rə-stikˈik/ adjective

Of (the nature of) tetrastichs

tetrasˈtichous adjective (botany)

In four rows

tetˈrastyle /-stīl/ noun

1. (Gr stȳlos a column) a building or portico with four columns supporting a ceiling in front
2. A group of four pillars

adjective

Having four columns

tetrasyllabic /-abˈik/ or tetrasyllabˈical adjective

tetrasyllable /-silˈə-bl/ noun

A word of four syllables

tetˈratheism /-thē-izm/ noun

(Gr theos god) the belief in four elements in the Godhead, ie the three persons of the Trinity and a divine essence out of which each of these originates

tetrathlon /te-trathˈlən/ noun

(Gr athlon contest) a four-event sporting contest

tetratomˈic adjective

Having or composed of four atoms to a molecule

tetravalent /ti-travˈə-lənt, tet-rə-vāˈlənt/ noun

Quadrivalent

tetraxon /ti-trakˈson/ noun

(Gr axōn, -onos an axis) a sponge spicule with four axes

tetrode /tetˈrōd/ noun

(Gr hodos a way) a thermionic valve with four electrodes

tetroxˈide noun

An oxide with four atoms of oxygen in the molecule

tetryl /tetˈril/ noun

A yellow crystalline explosive compound used as a detonator