-tactic or -taxial [from Greek taxis arrangement, order] (1) pertaining to arrangement, order, pattern (chaetotactic); (2) pertaining to movement of an organism in response to a stimulus of the type indicated by the stem or prefix (barotactic).

-tarsal [from Greek tarsos podos flat of the foot] Denotes the tarsus (tibiotarsal).

-taxia or -taxis or -taxy [from Greek taxis arrangement, order] (1) arrangement, order, pattern (chaetotaxy, heterotaxis, homotaxis); (2) movement of an organism in response to a stimulus of the type indicated by the stem or prefix (barotaxis, phototaxis).

-thallus (pl -thalli) or -thallium (pl -thallia). [from Latin thallus young green branch or shoot] Indicates a young branch or shoot of the type indicated by the stem or prefix (prothallium).

-thamnia or -thamnus [from Greek thamnos bush, shrub] Denotes a shrub with the characteristic indicated by the stem or prefix (Lepidothamnus).

-theca (pl -thecae) [from Latin theca case, box, cover, envelope, container] Containing structure, covering, or sheath, of the type indicated by the stem or prefix (ootheca).

-thecium (pl -thecia). [from Latin theca case, box, cover, envelope, container] Small containing structure, covering, or sheath, of the type indicated by the stem or prefix (acrothecium).

-there (also -therian) [from Greek therion wild animal] Beast, mammal (titanothere).

-therium (pl -theria) [from Greek therion wild animal] In taxonomic names: Beast, mammal (Prototheria).

-therm [from Greek therme heat] An animal having the mode of temperature regulation indicated by the stem or prefix (endotherm).

-thermia [from Greek therme heat] Having the temperature level indicated by the stem or prefix (hypothermia).

-thymia [from Greek thymos mind, spirit] The condition of the mind indicated by the stem or prefix (schizothymia).

-tibial [from Latin tibia pipe, shinbone] Denotes the tibia (femorotibial).

-tic See: -ic.

-tion See: -ion.

-tokous [from Greek tokeus father, sire] Producing, bearing (arrhenotokous).

-toky [from Greek tokeus father, sire] Parentage, production, bearing, reproduction (thelytoky).

-tome [from Greek tomeus one that cuts] (1) cutting instrument (microtome); (2) part, section (gonotome).

-tomy [from Greek tomos cutting, sharp] (1) cutting, incision (lobotomy).

-topia [from Greek topos place] Denotes the state of being in a place or location (ectopia).

-topic [from Greek topos place] Denotes placement or location (ectopic pregnancy).

-toxic [from Latin toxicum poison] Poisonous, toxic (fetotoxic).

-toxin [from Latin toxicum poison] A toxin of the type indicated by the stem or prefix (batrachotoxin, hemotoxin, neurotoxin).

-trope [from Greek tropos turn, direction, way] One exhibiting a tropism in response to the sort of stimulus indicated by the stem or prefix (heliotrope).

-troph [from Greek trophe nourishment, food] One nourished or growing in the manner indicated by the the stem or prefix (autotroph).

-trophic [from Greek trophe nourishment, food] Nourished or growing in the manner indicated by the the stem or prefix (autotroph).

-trophy [from Greek trophe nourishment, food] Nourishment or growth of the type indicated by the the stem or prefix (atrophy).

-tropia or -tropism or -tropy [from Greek tropos turn, direction, way] The manifestation of a tropism in response to the sort of stimulus indicated by the stem or prefix (phototropism).

-tropic or -tropous [from Greek tropos turn, direction, way] Exhibiting a tropism in response to the sort of stimulus indicated by the stem or prefix (homotropous).

-tropium [from Greek tropos turn, direction, way] An organism exhibiting a tropism in response to the stimulus indicated by the stem or prefix (Heliotropium).

-ty [English equivalent of Latin -tas] Quality, state, condition (toxicity).

-type [from Latin typus figure, pattern, type, model] Something that is a figure, pattern, type, or model of the kind indicated by the stem or prefix (karyotype).

-typic [from Latin typus figure, pattern, type, model] Of or pertaining to the kind of figure, pattern, type, or model indicated by the stem or prefix (karyotypic, polytypic).

-typy [from Latin typus figure, pattern, type, model] Condition of being a figure, pattern, type, or model of the kind indicated by the stem or prefix (homotypy).

-ula or -ulae or -ule or -ulum or -ulus [English -ule from Latin diminutive endings -ulus, -ula, -ulum, -ulae] Small one(s) (blastula).

-ulnar [from Latin ulna forearm] Denotes the ulna (humeroulnar, radioulnar).

-um See: -ium.

-ura or -uran or -urus [from Greek oura tail] One(s) having the condition of the tail(s) indicated by the stem or prefix (Anura).

-uria [from Greek ouron urine] Denotes a condition of the urine (albuminuria, phenylketonuria, pyuria, saccharuria).

-valent [from Latin valens potent] During synapsis in meiotic prophase I: composed of the number of homologous chromosomes indicated by the prefix (bivalent, quadrivalent, trivalent).

-vora [from Latin vorare to swallow, devour] In taxonomic names: One that eats the thing indicated by the prefix or stem (Carnivora, Insectivora).

-vore [from Latin vorare to swallow, devour] An organism that eats the thing indicated by the prefix or stem (carnivore, insectivore).

-vorous [from Latin vorare to swallow, devour] Eating the thing indicated by the prefix or stem (carnivorous, insectivorous).

-ward or -wards [from Old English suffix -weard; of Germanic origin, but related to Latin vertere to turn] In the direction of the the thing indicated by the stem or prefix (upward, homewards, toward).

-xylon [from Greek xylon wood] (1) in taxonomic names: organism(s) having wood of a type or a relationship to wood of a type indicated by the stem or prefix; (2) wood (Trochetiopsis erythroxylon).

-yl In chemistry: denotes a radical (methyl).

-ylene In chemistry: denotes a bivalent hydrocarbon radical (methylene).

-zoa (sing -zoan) [from Greek zoon animal] Denotes animals or, more broadly, living things (protozoa).

-zoic [-zoa + -ic] (1) having the animal mode of existence indicated by the stem or prefix (coprozoic); (2) relating to animal life or, more broadly, to life of any kind (Mesozoic).

-zygous [from Greek zygon yoke, tying element] (1) yoked; (2) having a zygotic nature of a sort indicated by the stem or prefix (heterozygous).

-zyme [from Greek zymosis fermentation] Enzyme (allozyme, enzyme).