plain in WordNet English dictionary

1. clearly revealed to the mind or the senses or judgment
   "the effects of the drought are apparent to anyone who sees the parched fields"; "evident hostility"; "manifest disapproval"; "patent advantages"; "made his meaning plain"; "it is plain that he is no reactionary"; "in plain view"
   apparent  evident  manifest  patent  plain  unmistakable 
   
2. lacking embellishment or ornamentation
   "a plain hair style"; "unembellished white walls"; "functional architecture featuring stark unornamented concrete"
   plain  bare  spare  unembellished  unornamented 
   
3. lacking in physical beauty or proportion
   "a homely child"; "several of the buildings were downright homely"; "a plain girl with a freckled face"
   homely  plain 
   
4. not elaborate or elaborated; simple
   "plain food"; "stuck to the plain facts"; "a plain blue suit"; "a plain rectangular brick building"
   plain 
   
5. lacking patterns especially in color
   plain  unpatterned 
   
6. free from any effort to soften to disguise
   "the plain and unvarnished truth"; "the unvarnished candor of old people and children"
   plain  unvarnished 
   
7. not mixed with extraneous elements
   "plain water"; "sheer wine"; "not an unmixed blessing"
   plain  sheer  unmingled  unmixed 
   

1. unmistakably (`plain' is often used informally for `plainly')
   "the answer is obviously wrong"; "she was in bed and evidently in great pain"; "he was manifestly too important to leave off the guest list"; "it is all patently nonsense"; "she has apparently been living here for some time"; "I thought he owned the property, but apparently not"; "You are plainly wrong"; "he is plain stubborn"
   obviously  evidently  manifestly  patently  apparently  plainly  plain  obviously  evidently  manifestly  patently  apparently  plainly  plain 
   

1. extensive tract of level open land
   "they emerged from the woods onto a vast open plain"; "he longed for the fields of his youth"
   plain  field  champaign 
   
2. a basic knitting stitch
   knit  knit stitch  plain  plain stitch 
   

1. express complaints, discontent, displeasure, or unhappiness
   "My mother complains all day"; "She has a lot to kick about"
   complain  kick  plain  sound off  quetch  kvetch