The word "antonymy" was coined by C. J. Smith as an opposite of "synonymy"

Gradable antonyms[edit]
A gradable antonym is one of a pair of words with opposite meanings where the two meanings lie on a continuous spectrum. Temperature is such a continuous spectrum so hot and cold, two meanings on opposite ends of the spectrum, are gradable antonyms. Other examples include: heavy : light, fat : skinny, dark : light, young : old, early : late, empty : full, dull : interesting.
Complementary antonyms[edit]
A complementary antonym, sometimes called a binary or contradictory antonym (Aarts, Chalker & Weiner 2014), is one of a pair of words with opposite meanings, where the two meanings do not lie on a continuous spectrum. There is no continuous spectrum between odd and even but they are opposite in meaning and are therefore complementary antonyms. Other examples include: mortal : immortal, exit : entrance, exhale : inhale, occupied : vacant.
Relational antonyms[edit]
A relational antonym is one of a pair of words that refer to a relationship from opposite points of view. There is no lexical opposite of teacher, but teacher and pupil are opposite within the context of their relationship. This makes them relational antonyms. Other examples include: husband : wife, doctor : patient, predator : prey, teach : learn, servant : master, come : go, parent : child.
Auto-antonyms[edit]
An auto-antonym is a word that can have opposite meanings in different contexts or under separate definitions:

• 
  enjoin (to prohibit, issue injunction; to order, command)
  
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  fast (moving quickly; fixed firmly in place)
  
• 
  cleave (to split; to adhere)
  
• 
  sanction (punishment, prohibition; permission)
  
• 
  stay (remain in a specific place, postpone; guide direction, movement)
  

Antonyms are words with opposite meaning. And antonymy refers to the relationship of oppositeness. Antonyms are exceedingly valuable in defining the exact meaning of a given word and its synonyms. Antonyms enable us to express briefly the opposite of a particular thought, often for the sake of contrast. From the linguistic point of view, one of the main concerns of studying antonymy is to determine the boundaries of antonymy. Antonymy has been divided into three different types by the linguists, that is, gradable antonymy, complementary antonymy and converse antonymy. Gradable antonymy is described as a relation, that is, “not A” doesn’t equal B. There is an intermediate form between A and B. Complementary antonymy is a relation that “not A” equals B. There is no intermediate ground between them. Converse antonymy refers to a kind of reversal relationship. Antonymy plays rather important roles in specific English texts, especially in poetry, novels, dramas, speeches and JOURNAL OF LANGUAGE TEACHING AND RESEARCH 237 © 2014 ACADEMY PUBLISHER proverbs. Antonymy helps the English textual cohesion. Employing antonyms in texts correctly reveals the oppositeness of the things and produces the strong sense of comparison. Therefore, writers are fond of and are good at employing the antonyms in their literature works, and it contributes to achieve characterization, scene description, statement of opinions, discussion and refutation. The linguistic study of antonymy in English texts helps readers understand and appreciate authors’ intention much more easily. Teachers who emphasize the study of antonymy in class will find their students have a higher reading ability. However, the study of antonymy should not stop at linguistic level. Probing into the rhetorical function of antonymy may help us improve the ability of using language and heighten the effect of language output.