T - Trauma, Toxic, Thermos, Theater, Therapy, Theory.

Trauma. From Ancient Greek τραῦμα, trauma, wound, damage. Any serious injury to the body, often resulting from violence or an accident. An emotional wound leading to psychological injury.

Derived or related words: traumatic, traumatize, traumatology.

Toxic. From Ancient Greek τοξικόν, toxikon, φάρμακον, pharmakon, poison for use on arrows. From τοξικός, toxikos, pertaining to arrows or archery, from τόξον, toxon, bow. Having a chemical nature that is harmful to health or lethal if consumed or otherwise entering into the body in sufficient quantities.

Derived or related words: toxicology, toxicity, toxin.

Thermos. From Ancient Greek θερμός, thermos, warm. A bottle which can keep liquids at a desired temperature. 

Derived or related words: thermometer (from thermos + meter, measuring the temperature), thermodynamic (from thermos + dynamic, conversion of heat into other forms of energy), thermoelectric (from thermos + electric, conversion of heat into electricity) thermostatic (from thermos + static, maintaining a consistent temperature).

Theater. From Ancient Greek θέατρον, théatron, a place for viewing. From θεάομαι, theáomai, to see, to watch, to observe.

Derived or related words: theatrical, theatricality.

 

Therapy. From Ancient Greek θεραπεία, therapia, medical treatment, from the verb θεραπεύω, therapeuō, I treat medically.
The treatment of a disease or a disability, physical or mental.

Derived or related words: therapeutic, therapist, chemotherapy, psychotherapy etc.

 

Theory. From Ancient Greek θεωρία, theōria, contemplation, speculation, from θεωρέω, theōreō, I look at, view, consider, examine. From θέα, thea, a view + ὁράω, horaō, I see, look. A mental conception, reflection, consideration.

Derived or related words: theorem, theoretical, theorize.