oblique

Etymology

From Middle French oblique, from Latin oblīquus (also spelled oblīcus) (“slanting, sideways, indirect, envious”).

adj

1. Not erect or perpendicular; not parallel to, or at right angles from, the base.
   when it has a Direction oblique to that of the former Motion, it is either added to, or subtracted from the former Motion 1725, George Cheyne, Philosophical Principles of Religion, page 16
2. Not straightforward; obscure or confusing.
   This mode of oblique research, where a more direct one is denied, we find to be the only one in our power. 1840, Thomas De Quincey, “Style. No. II”, in Blackwood's Edinburgh Magazine, page 387
3. Disingenuous; underhand; morally corrupt.
   For the love we bear our friends, / Tho nere so strongly grounded, / Hath in it certain oblique ends / If to the bottome sounded 1630, Michael Drayton, “The Third Nimphall”, in The Muses Elyzium
   Then would be closed the restless, oblique eye / That looks for evil, like a treacherous spy 1849, William Wordsworth, “Humanity”, in The Poetical Works of William Wordsworth
4. Not direct in descent; not following the line of father and son; collateral.
   His natural affection in a direct line was strong; in an oblique, but weak; for no man ever loved Children more, or a Brother less. 1665, Richard Baker, “The Reign of King Henry the First”, in A Chronicle of the Kings of England, page 49
5. (botany, of leaves) Having the base of the blade asymmetrical, with one side lower than the other.
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   Leaves long, lanceolate, tapering upward from the middle to an acute point, […] secondaries very oblique, distinct, alternate, parallel, curved in transversing the blade 1892, Leo Lesquereux, The Flora of the Dakota Group, page 78
6. (botany, of branches or roots) Growing at an angle that is neither vertical nor horizontal.
   Oblique and sinker roots will normally be under a greater compression stress than lateral roots. 1997, A. Stokes, D. Guitard, “Tree Root Response to Mechanical Stress”, in Arie Altman, Yoav Waisel, editors, Biology of Root Formation and Development, page 233
7. (grammar) Pertaining to the oblique case (non-nominative).
8. (grammar, of speech or narration) Indirect; employing the actual words of the speaker but as related by a third person, having the first person in pronoun and verb converted into the third person and adverbs of present time into the past, etc.
9. (music) Employing oblique motion, motion or progression in which one part (voice) stays on the same note while another ascends or descends.
   In passing from the minor third to unison, the motion ought to be oblique, but from the major third to unison the motion ought to be similar 1837, Allan Cunningham, “Music”, in The Popular Encyclopedia, page 109

noun

1. (geometry) An oblique line.
2. (typography) Synonym of slash ⟨/⟩.
   Initial inquiries among professional typists uncover names like slant, slant line, slash, and slash mark. Examination of typing instruction manuals discloses additional names such as diagonal and diagonal mark, and other sources provide the designation oblique. 1965, Dmitri A. Borgmann, Language on Vacation, page 240
   Other Chaucerian manuscripts had the virgule (or virgil or oblique: /) at the middle of lines. 1990, John McDermott, Punctuation for Now, page 20
3. (grammar) The oblique case.

verb

1. (intransitive) To deviate from a perpendicular line; to become askew;
   he sat upon the edge of his chair […] and achieved a communication with his plate by projecting his person towards it in a line which obliqued from the bottom of his spine 1814, Sir Walter Scott, Waverly
2. (military) To march in a direction oblique to the line of the column or platoon; — formerly accomplished by oblique steps, now by direct steps, the men half-facing either to the right or left.
3. (transitive, computing) To slant (text, etc.) at an angle.