| A | B |
|---|
| symbiosis | The close association between two or more different organisms of different species, often but not necessarily benefiting each member |
| tariff | A government tax on imports or exports |
| technique | A procedure or method for accomplishing a complicated task |
| tempo | A characteristic rate or rhythm of something; a pace |
| toxin | A poisonous substance produced by a living organism |
| tranquility | The quality or condition of being free from disturbance |
| tumult | Noisy and disorderly activity |
| tundra | A vast treeless plain in the Arctic regions where the subsoil is permanently frozen |
| ultraviolet | Having or employing wavelengths shorter than light but longer than X-rays; lying outside the visible spectrum at its violet end |
| unanimous | Sharing the same opinion; being fully in agreement |
| undulate | To have a wavy appearance or form |
| vaccine | A substance that stimulates cells in the immune system to attack disease-causing agents |
| vacillate | To be unable to decide between one opinion or course of action and another |
| vertebrate | Any of a large group of animals having a backbone; including fishes, amphibians, reptiles, birds, and mammals |
| virtuoso | A person of great skill or technique |
| voracious | Eating or eager to eat great amounts of food |
| wretched | Very unhappy or unfortunate; miserable |
| xylem | A plant tissue that carries water and dissolved minerals up from the roots through the stem to the leaves |
| yacht | Any of various small sailing or motor-driven vessels used for pleasure trips or racing |
| zoology | The branch of biology that deals with animals |
