singular vs plural - "I'm wearing a red PANT." or "I'm wearing a red PANTS."

Is correct to use "Pant" or is "Pants" better?

Here the phrase below:

I'm wearing a red pants.

Answer

Individual items of clothing which consist of two components (one for each side of the body), often have no singular form, and are always treated as plural even though they are a single unit. Thus, you would wear red pants or wear a pair of red pants.

---

There are numerous English words which are always treated as plural: scissors, congratulations, outskirts, jitters, forceps, savings, suds, etc.— too many to cover in one answer. But if we limit it to clothes (itself always plural), I can suggest these guidelines:

• 
  

  most garments for the lower body which cover the legs individually are always plural: trousers, shorts, overalls, breeches, chaps, bloomers, etc. Even a one-legged person would not wear "a" jodphur or sweatpant or boardshort; he or she wears jodphurs, sweatpants, or boardshorts. The explanation behind it is that tailors made them in two pieces, one for each leg, and so they always came to be referred to in the plural; a shirt or coat, in contrast, was made from a single piece of cloth.

  
  

  Terms referring to specific types or expressions of those garments also take the plural: dungarees, chinos, bell bottoms, and so forth. Indeed, even derivates and brand name uses follow this pattern, whether in the name itself (e.g. Dockers®) or by synecdoche: what comes between me and my Calvins? (i.e. my Calvin Klein jeans).

  
  

  In contrast, items which come as a pair of separate pieces follow regular pluralization: one mitten, one pair of mittens, two mittens.

  
  


• 
  

  suspenders / braces. In AmE, braces when referring to the orthodontic devices are also always plural; I'm not sure about BrE.

  
  



• 
  

  pajamas (AmE) / pyjamas (BrE) and derived nicknames like jammies, PJs, or jim-jams.

  
  


• 
  

  some lower body undergarments with legs or where a separate gap is provided for each leg: pants (BrE) / panties (AmE), boxers, drawers, long johns, jockies, knickers, briefs (inc. "tighty-whities"), tights, thermals— but not, for example, pantyhose, a jockstrap, or a thong.

  
  


• 
  

  eye and ear accessories consisting of single piece but with a separate component for each eye— [eye]glasses, binoculars, bifocals, contacts, shades, etc.— or each ear— earmuffs, headphones, cans. In contrast, you can have a singular monocle, eyepatch, or scope; one earring or one earbud. Headset is an exception.

  
  

Note finally that in some cases, a singular form of the word does exist, but it refers to something different: glasses and glass, slacks and slack, trunks and trunk, "Daisy Dukes" and Daisy Duke.