From Middle English smothe, smethe, from Old English smēþe, smōþ, both from Proto-West Germanic *smanþī, of unknown origin.

• IPA: /smuːð/

smooth (comparative smoother, superlative smoothest)

1. Having a texture that lacks friction. Not rough.
   • 1695, C[harles] A[lphonse] du Fresnoy, translated by John Dryden, De Arte Graphica. The Art of Painting, […], London: […] J[ohn] Heptinstall for W. Rogers, […], →OCLC ↗:

     The outlines must be smooth, […] imperceptible to the touch, and even, without eminence or cavities.

   • 1907 August, Robert W[illiam] Chambers, chapter IX, in The Younger Set, New York, N.Y.: D. Appleton & Company, →OCLC ↗:

     “A tight little craft,” was Austin’s invariable comment on the matron; and she looked it, always trim and trig and smooth of surface like a converted yacht cleared for action. ¶ Near her wandered her husband, orientally bland, invariably affable, […].

2. Without difficulty, problems, or unexpected consequences or incidents.

   We hope for a smooth transition to the new system.

3. Bland; glib.
   • 1712 (date written), [Joseph] Addison, Cato, a Tragedy. […], London: […] J[acob] Tonson, […], published 1713, →OCLC ↗, (please specify the page):

     This smooth discourse and mild behavior oft / Conceal a traitor.

4. Flowing or uttered without check, obstruction, or hesitation; not harsh; fluent.
   • 1670, John Milton, The History of Britain:

     the only smooth poet of those times

   • 1737, [Alexander Pope], The First Epistle of the Second Book of Horace, Imitated, London: […] T. Cooper, […], →OCLC ↗, page 16 ↗:

     VValler vvas ſmooth; but Dryden taught to join / The varying verſe, the full reſounding line, / The long majetſic march, and energy divine.

   • 1713 (indicated as 1714), [John] Gay, “Book III”, in The Fan. A Poem. […], London: […] J[acob] Tonson, […], →OCLC ↗, page 23 ↗:

     VVhen bright Minerva roſe, / From her ſvveet Lips ſmooth Elocution flovvs, […]

5. Suave; sophisticated.
6. (of an action) Natural; unconstrained.
7. (of a motion) Unbroken.
8. (chiefly, of water) Placid, calm.
9. (of an edge) Lacking projections or indentations; not serrated.
10. (of food or drink) Not grainy; having an even texture.
11. (of a beverage) Having a pleasantly rounded flavor; neither rough nor astringent.
12. (mathematics, of a function) Having derivatives of all finite orders at all points within the function’s domain.
13. (math, of a number) That factors completely into small prime numbers.
14. (linguistics, classical studies, of a vowel) Lacking marked aspiration.
15. (of muscles, medicine) Involuntary and non-striated.

• (having a texture lacking friction) even
• (without difficulty or problems) fluid

• rough
• uneven
• bumpy

• French: lisse
• German: glatt
• Italian: liscio, mellifluo
• Portuguese: liso
• Russian: гла́дкий
• Spanish: liso

• French: doux, facile
• German: reibungslos, problemlos, glatt
• Italian: facile, dolce, soffice
• Portuguese: suave
• Russian: гла́дкий

• French: lisse
• German: glatt
• Italian: blando
• Portuguese: suave

• French: sophistiqué
• Spanish: sofisticado

• French: naturel
• Portuguese: suave

• French: souple
• Russian: пла́вный
• Spanish: constante

• Spanish: tranquilo, apacible

• Portuguese: liso
• Spanish: liso

• Portuguese: suave
• Spanish: suave

• French: régulier
• German: glatt
• Portuguese: suave

• French: douce

smooth (comparative smoother, superlative smoothest)

1. Smoothly.
   • 1591 (date written), William Shakespeare, “The Second Part of Henry the Sixt, […]”, in Mr. William Shakespeares Comedies, Histories, & Tragedies. […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC ↗, [Act III, scene ii]:

     Smooth runs the water where the brook is deep.

smooth (plural smooths)

1. Something that is smooth, or that goes smoothly and easily.
   • 1611, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], →OCLC ↗, Genesis 27:16 ↗:

     The smooth of his neck.

   • 1861 January – 1862 August, W[illiam] M[akepeace] Thackeray, The Adventures of Philip on His Way through the World; […], volume (please specify |volume=I to III), London: Smith, Elder and Co., […], published 1862, →OCLC ↗:

     I think you and I will take the ups and the downs , the roughs and the smooths of this daily existence and conversation

2. A smoothing action.
3. A domestic animal having a smooth coat.
4. A member of an anti-hippie fashion movement in 1970s Britain.
5. (statistics) The analysis obtained through a smoothing procedure.

smooth (smooths, present participle smoothing; simple past and past participle smoothed)

1. (transitive) To make smooth or even.

   Synonyms: smoothen

2. (transitive) To reduce to a particular shape or form by pressure; to press, to flatten.

   to smooth cloth with a smoothing iron

3. (transitive) To make straightforward or easy.
   • 2007, Beth Kohn, Lonely Planet Venezuela, page 379:

     Caracas can be a tough place but the tremendously good-natured caraqueños smoothed my passage every step of the way.

4. (transitive) To calm or palliate.

   to smooth a person's temper

5. (statistics, image processing, digital audio) To capture important patterns in the data, while leaving out noise.
6. (West Country) To stroke; especially to stroke an animal's fur.

   Can I smooth your cat?

• French: lisser
• German: glätten
• Portuguese: alisar
• Spanish: alisar

• French: lisser
• German: glätten