1. third base the base that must be touched third by a base runner in baseball
  2. third house a group of people who try actively to influence legislation
  3. thrombose become blocked by a thrombus
  4. threadbare thin and tattered with age
  5. third baseman (baseball) the person who plays third base
  6. third power the product of three equal terms
  7. thrombus a blood clot formed within a blood vessel and remaining attached to its place of origin
  8. thirties the time of life between 30 and 40
  9. database an organized body of related information
  10. third class inexpensive accommodations on a ship or train
  11. third-rate of lesser quality than second-rate
  12. thorough bass a bass part written out in full and accompanied by numbers to indicate the chords to be played
  13. third person pronouns and verbs that are used to refer to something other than the speaker or addressee of the language in which they occur
  14. thwartwise extending or lying across
  15. dirt bike a lightweight motorcycle equipped with rugged tires and suspension; an off-road motorcycle designed for riding cross country or over unpaved ground
  16. third party someone other than the principals who are involved in a transaction
  17. dirt ball a person who has a nasty or unethical character undeserving of respect
  18. thyroiditis inflammation of the thyroid gland
  19. thrips any of various small to minute sucking insects with narrow feathery wings if any; they feed on plant sap and many are destructive
  20. Edward Pusey English theologian who founded the Oxford movement