SYNONYM, ANTONYM AND HYPONYM

SYNONYMS 

Synonyms are different words which have the same meaning, or almost the same meaning.

The words stones and rocks are synonyms.

Synonyms can be nouns, verbs, adverbs or adjectives, as long as both are the same part of speech.

For example:
- chair and seat (nouns)
- go and leave (verbs)
- quickly and rapidly (adverbs)
- long and extended (adjectives)

Synonyms need not be single words, as in war and armed conflict.

Here are more synonyms:

- tremendous and remarkable
- cat and feline
- baby and infant
- sick and ill
- quickly and speedily

A word can have more than one synonym depending on which meaning you use for the word.
For example:
- expired could have the synonym no longer fresh, if you mean milk that's past its sale date.
- expired could have the synonym dead, if you mean no longer alive.

ANTONYMS 
Antonyms are words which have opposite meanings.

The words hot and cold are antonyms. So are up and down, and short and tall.

A word can have more than one antonym, depending on which meaning you use for the word.
For example:
- short could have the antonym tall if you are referring to a person's height.
- short could have the antonym long if you are referring to to the length of something.

In many languages, including English, you can sometimes make antonyms by adding a prefix:
- real and unreal are antonyms
- flexible and inflexible are antonyms
However, English is well known for its exceptions to the rules, so you have to watch out for words like flammable and inflammable, where this doesn't work ... they're synonyms!

There are actually four types of antonyms: 

• Gradable antonyms are opposites at either end of the spectrum, as in slow andfast.
• Complementary antonyms are absolute opposites, like mortal and immortal.
• Relational antonyms are opposites where one word describes a relationship between two objects, and the other word describes the same relationship when the two objects are reversed.
     For example, parent and child, teacher and student, or buy and sell.
• Auto-antonyms are the same two words that mean the opposite.
     For example, fast (moving quickly) and fast (stuck in place).

HYPONYM, also subordinate term. A WORD, PHRASE, or LEXEME of narrower or more specific meaning that comes ‘under’ another of wider or more general meaning: for example, rose under flower (‘a rose is a kind of flower’, ‘flowers include roses and tulips’). In this relationship, the word flower is a hyperonym, generic term, or superordinate term. Many hyponyms belong in groups, such as carpet, chair, desk, table, rug, stool, all of which are co-hyponyms of the hyperonym furniture (‘a carpet is an item of furniture’). Hyponymic relations are often imprecise, unstable, and multidimensional, depending on both context and how relationships are analysed. The same word may be a hyponym of several superordinates: axe as ‘kind of tool’ and ‘kind of weapon’; weapon also a hyponym of tool (‘a weapon is a kind of tool’). Battle-axe is ‘a kind of axe’ and ‘a kind of weapon’, but is unlikely to appear under axe in the SENSE of ‘a kind of tool’. Rug is in some contexts a synonym of carpet (‘The cat sat on the rug/carpet’), in others a hyponym of carpet (‘a rug is a kind of carpet’). See -ONYM, SEMANTICS.

http://www.worsleyschool.net/socialarts/synonyms/page.html
http://www.teachit.co.uk/armoore/lang/semantics.htm#14

http://www.encyclopedia.com/doc/1O29-HYPONYM.html