from The American Heritage® Dictionary of the English Language, 4th Edition

  • adj. Exhaustively complete: a thorough search.
  • adj. Painstakingly accurate or careful: thorough research.
  • adj. Absolute; utter: a thorough pleasure.
  • prep. Archaic Variant of through.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • adj. painstaking and careful not to miss or omit any detail
  • adj. utter; complete; absolute
  • n. A furrow between two ridges, to drain off the surface water.

from the GNU version of the Collaborative International Dictionary of English

  • adj. Passing through.
  • adj. Passing through or to the end; hence, complete; perfect.
  • adv. Thoroughly.
  • adv. Through.
  • n. A furrow between two ridges, to drain off the surface water.
  • prep. Through.

from The Century Dictionary and Cyclopedia

  • Through. See through, a later form of thorough, now the exclusive form as a preposition and adverb.
  • Through: as, thoroughgoing. See through, adverb
  • Going through; through, in a literal sense: a form now occurring only in dialectal use or in certain phrases and compounds. See through, adjective
  • Going through, as to the end or bottom of anything; thoroughgoing.
  • Leaving nothing undone; slighting nothing; not superficial.
  • Fully executed; having no deficiencies; hence, complete in all respects; unqualified; perfect.
  • Earnest; ardent. [Rare.]
  • n. That which goes through.
  • n. A furrow between two ridges.
  • n. Same as perpend.
  • n. In Brit. hist., in the reign of Charles I., the policy of Strafford and Laud of conducting or carrying through (‘thorough’) the administration of public affairs without regard to obstacles. Hence the word is associated with their system of tyranny.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adj. painstakingly careful and accurate
  • adj. performed comprehensively and completely


Middle English thorow, through, thorough, from Old English thuruh, from end to end, through; see terə-2 in Indo-European roots.
(American Heritage® Dictionary of the English Language, Fourth Edition)
Old English þuruh. (Wiktionary)
A disyllabic form of Old English þurh ("through"). (Wiktionary)



Log in or sign up to get involved in the conversation. It's quick and easy.