Etymology From Middle English thoruȝ, þoruȝ, from Old English þuruh, a byform of Old English þurh, whence comes English through. The adjective derives from the preposition and adverb. The word developed a syllabic form in cases where the word was fully stressed: when it was used as an adverb, adjective, or noun, and less commonly when used as a preposition.
1
Painstaking and careful not to miss or omit any detail.
The Prime Minister announced a thorough investigation into the death of a father-of-two in police custody.
Not enough! Your work has to be thorougher than this.
2 more examples
It's the most thorough artwork I have ever seen!
The infested house needs a thorough cleansing before being inhabitable again.
2
Utter; complete; absolute.
Dr. Oldfield once said to me, 'You talk to me quite all right, but why is it that you never open your lips at a committee meeting? You are a drone.' I appreciated the banter. The bees are ever busy, the drone is a thorough idler.1925–29, Mahatma Gandhi, “Shyness My Shield” (chapter XVIII), in Mahadev Desai, transl., The Story of My Experiments with Truth, Part I (Autobiography), Ahemadabad: Navajivan Mudranalaya, →ISBN:
Etymology From Middle English thoruȝ, þoruȝ, from Old English þuruh, a byform of Old English þurh, whence comes English through. The adjective derives from the preposition and adverb. The word developed a syllabic form in cases where the word was fully stressed: when it was used as an adverb, adjective, or noun, and less commonly when used as a preposition.
Ye might haue ſeene the frothy billowes fry Vnder the ſhip, as thorough them ſhe went […]1590, Edmund Spenser, “Book II, Canto XII”, in The Faerie Queene. […], London: […] [John Wolfe] for William Ponsonbie, →OCLC:
You are contented to be led in triumph Thorough the streets of Rome?1599 (first performance), William Shakespeare, “The Tragedie of Iulius Cæsar”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC, [Act V, scene i], line 109:
1 more example
At length did cross an Albatross: / Thorough the fog it came; […]1797–1798 (date written; revised 1817), S[amuel] T[aylor] Coleridge, “The Rime of the Ancient Mariner. In Seven Parts.”, in Sibylline Leaves: A Collection of Poems, London: Rest Fenner, […], published 1817, →OCLC, page 6:
thorough
noun
Etymology From Middle English thoruȝ, þoruȝ, from Old English þuruh, a byform of Old English þurh, whence comes English through. The adjective derives from the preposition and adverb. The word developed a syllabic form in cases where the word was fully stressed: when it was used as an adverb, adjective, or noun, and less commonly when used as a preposition.
1
UK, Dialectal A furrow between two ridges, to drain off the surface water.
The Ignorance and Idleness of the Plowman, who either goes so shallow, or plows his Thoroughs so wide, or misses Part of the Ground.1733, William Ellis, Chiltern And Vale Farming Explained: