• enPR: plān, IPA: /pleɪn/, [pl̥eɪn]

From Middle English pleyn, borrowed from Anglo-Norman pleyn, playn, Middle French plain, plein, and Old French plain, from Latin plānus.

plain (comparative plainer, superlative plainest)

1. (now rare, regional) Flat, level. [from 14th c.]
   • 1611, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], →OCLC ↗, Isaiah 40:4 ↗:

     The crooked shall be made straight, and the rough places plain.

2. Simple, unaltered.
   1. Ordinary; lacking adornment or ornamentation; unembellished. [from 14th c.]

      He was dressed simply in plain black clothes.

      a plain tune

   2. Of just one colour; lacking a pattern.

      a plain pink polycotton skirt

   3. Simple in habits or qualities; unsophisticated, not exceptional, ordinary. [from 16th c.]

      They're just plain people like you or me.

      • 1654, Henry Hammond, Of Fundamentals:

        plain yet pious Christians

      • 1861, Abraham Lincoln, Message to Congress in Special Session, July 4th:

        the plain people

   4. (of food) Having only few ingredients, or no additional ingredients or seasonings; not elaborate, without toppings or extras. [from 17th c.]

      Would you like a poppy bagel or a plain bagel?

   5. (computing) Containing no extended or nonprinting characters (especially in plain text). [from 20th c.]
3. Obvious.
   1. Evident to one's senses or reason; manifest, clear, unmistakable. [from 14th c.]
      • 1843 April, Thomas Carlyle, “ch. XV, Practical — Devotional”, in Past and Present, American edition, Boston, Mass.: Charles C[offin] Little and James Brown, published 1843, →OCLC ↗, book II (The Ancient Monk):

        In fact, by excommunication or persuasion, by impetuosity of driving or adroitness in leading, this Abbot, it is now becoming plain everywhere, is a man that generally remains master at last.

   2. Downright; total, unmistakable (as intensifier). [from 14th c.]

      His answer was just plain nonsense.

4. Open.
   1. Honest and without deception; candid, open; blunt. [from 14th c.]

      Let me be plain with you: I don't like her.

      • c. 1603–1606, William Shakespeare, “The Tragedie of King Lear”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC ↗, [Act II, scene v]:

        an honest mind, and plain, he must speak truth

      • 1749, Henry Fielding, The History of Tom Jones, a Foundling, volume (please specify |volume=I to VI), London: A[ndrew] Millar, […], →OCLC ↗:

        The Quaker was no sooner assured by this fellow of the birth and low fortune of Jones, than all compassion for him vanished; and the honest plain man went home fired with no less indignation than a duke would have felt at receiving an affront from such a person.

   2. Clear; unencumbered; equal; fair.
      • 1711, Henry Felton, Dissertation on Reading the Classics:

        Our troops beat an army in plain fight.

5. Not unusually beautiful; unattractive. [from 17th c.]

   Throughout high school she worried that she had a rather plain face.

6. (card games) Not a trump.

• (lacking adornment or ornamentation) no-frills, simple, unadorned, unseasoned; see also Thesaurus:bare-bones
• (of just one colour) monochrome
• (not exceptional) normal, ordinary
• (obvious) blatant, ostensible; see also Thesaurus:obvious or Thesaurus:explicit
• (intensifier) consarn, darned, stinking; see also Thesaurus:damned
• (honest and without deception) frank, sincere; see also Thesaurus:honest

• bells and whistles
• decorative
• exotic
• fancy
• ornate

• plane
• planar

• French: simple
• German: schlicht
• Italian: semplice
• Portuguese: simples
• Russian: просто́й
• Spanish: sencillo

• French: uni

• French: nature
• German: Natur
• Italian: al naturale (of food), in bianco (of pasta or rice)
• Portuguese: natural, insípido
• Spanish: desabrido, natural

• French: simple texte
• Portuguese: simples
• Spanish: con caracteres normales, libre de caracteres especiales, sin caracteres especiales

plain (not comparable)

1. (colloquial) Simply.

   It was just plain stupid.

   I plain forgot.

2. (archaic) Plainly; distinctly.

   Tell me plain: do you love me or no?

From Old French plain, from Latin plānum, neuter substantive from plānus.

plain (plural plains)

1. An expanse of land with relatively low relief and few trees, especially a grassy expanse.
   • 1667, John Milton, “Book I”, in Paradise Lost. […], London: […] [Samuel Simmons], and are to be sold by Peter Parker […]; [a]nd by Robert Boulter […]; [a]nd Matthias Walker, […], →OCLC ↗; republished as Paradise Lost in Ten Books: […], London: Basil Montagu Pickering […], 1873, →OCLC ↗:

     Him the Ammonite / Worshipped in Rabba and her watery plain.

   • 1961, J. A. Philip. Mimesis in the Sophistês of Plato. In: Proceedings and Transactions of the American Philological Association 92. p. 467.

     For Plato the life of the philosopher is a life of struggle towards the goal of knowledge, towards “searching the heavens and measuring the plains, in all places seeking the nature of everything as a whole”

   Synonyms: flatland, grassland
   Hypernyms: land, terrain
   Hyponyms: prairie, steppe
2. A broad, flat expanse in general, as of water.
   • 1850, [Alfred, Lord Tennyson], In Memoriam, London: Edward Moxon, […], →OCLC ↗, Canto IX:

     Fair ship, that from the Italian shore,
     ⁠Sailest the placid ocean-plains
     ⁠With my lost Arthur’s loved remains,
     Spread thy full wings, and waft him o’er.

3. (archaic) Synonym of field in reference to a battlefield.
   • 1899, Alexander John Arbuthnot, Lord Clive: The Foundation of British Rule in India:

     You have stormed no town and found the money there ; neither did you find it in the plains of Plassey after the defeat of the Nawab

   • c. 1593 (date written), William Shakespeare, “The Tragedy of Richard the Third: […]”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC ↗, [Act V, scene iii]:

     Lead forth my soldiers to the plain.

4. (obsolete) Alternative spelling of plane: a flat geometric field.

• French: plaine
• German: Ebene
• Italian: pianura
• Portuguese: planície
• Russian: равни́на
• Spanish: llanura, planicie

plain (plains, present participle plaining; simple past and past participle plained)

1. (obsolete, transitive) To level; to raze; to make plain or even on the surface.
   • 1594, Christopher Marlow[e], The Troublesome Raigne and Lamentable Death of Edward the Second, King of England: […], London: […] [Eliot’s Court Press] for Henry Bell, […], published 1622, →OCLC ↗, (please specify the page):

     Frownst thou thereat aspiring Lancaster,
     The sworde shall plane the furrowes of thy browes,

   • 1612, George Wither, Prince Henrie’s Obsequies, Elegy 24, in Egerton Brydges (editor), Restituta, Volume I, London: Longman, Hurst, Rees, Orme & Brown, 1814, p. 399,

     Though kept by Rome’s and Mahomet’s chiefe powers;
     They should not long detain him there in thrall:
     We would rake Europe rather, plain the East;
     Dispeople the whole Earth before the doome:

2. (obsolete, transitive) To make plain or manifest; to explain.
   • c. 1607–1608, William Shakeſpeare, The Late, And much admired Play, Called Pericles, Prince of Tyre. […], London: Imprinted at London for Henry Goſſon,  […], published 1609, →OCLC ↗, [Act III, Prologue] ↗:

     What’s dumb in show, I’ll plain with speech.

From Anglo-Norman plainer, pleiner, variant of Anglo-Norman - and Old French pleindre, plaindre, from Latin plangere, present active infinitive of plangō.

plain (plural plains)

1. (rare, poetic) A lamentation.
   • 1815, Sir Walter Scott, The Lady of the Isles‎, Canto IV, part IX:

     The warrior-threat, the infant's plain,
     The mother's screams, were heard in vain;

plain (plains, present participle plaining; simple past and past participle plained)

1. (reflexive, obsolete) To complain. [13th–19th c.]
   • c. 1370–1390, [William Langland], “[Prologue]”, in The Vision of Pierce Plowman [...], London: […] Roberte Crowley, […], published 1550, →OCLC ↗:

     Persones and parisch prestes · pleyned hem to þe bischop / Þat here parisshes were pore · sith þe pestilence tyme […].

     (please add an English translation of this quotation)

2. (ambitransitive, now, rare, poetic) To lament, bewail. [from 14th c.]

   to plain a loss

   • 1595, Ed. Spencer [i.e., Edmund Spenser], “Astrophel. A Pastoral Elegie vpon the Death of the Most Noble and Valorous Knight, Sir Philip Sidney.”, in Colin Clouts Come Home Againe, London: […] T[homas] C[reede] for William Ponsonbie, →OCLC ↗:

     Shepheards, that wont […]
     Oft times to plaine your loves concealed smart

   • c. 1600, John Ayliffe, Satires:

     Thy mother could thee for thy cradle set
     Her husband's rusty iron corselet;
     Whose jargling sound might rock her babe to rest,
     That never plain'd of his uneasy nest.

   • 1834, L[etitia] E[lizabeth] L[andon], chapter II, in Francesca Carrara. […], volume III, London: Richard Bentley, […], (successor to Henry Colburn), →OCLC ↗, page 9 ↗:

     Then, again, she almost thought that the soft and wailing wind which swept mournfully through the sepulchral boughs of the large old yews, had a voice not of this world—was it the inarticulate plaining of her brother's gentle spirit, debarred from intercourse, but still keeping over her the deep and eternal watch of love?

   • 1936, Alfred Edward Housman, More Poems, "XXV", lines 5–9

     Then came I crying, and to-day, / With heavier cause to plain, / Depart I into death away, / Not to be born again.

From Middle English pleyn, borrowed from Old French plein, from Latin plēnus.

plain (comparative plainer, superlative plainest)

1. (obsolete) Full, complete in number or extent.

1. Surname.