The word Synonyms comes from Ancient Greek σÏν ("syn") "with" and νομα ("onoma") "name." Synonymy can be defined as the semantic relation that holds between two words that can express the same meaning, in other words, synonyms are different words with similar meanings. Synonyms can be any part of speech (e.g. nouns, verbs, adjectives, adverbs or prepositions), as long as both members of the pair are the same part of speech such as: noun "baby" and "infant", verb "buy" and "purchase", adjective "pretty" and "attractive", adverb "rapidly" and "speedily". That means if the two words have same meaning then they should refer to the same reference in contexts. It is true that in specific sentences one word can replace its synonym without changing the meaning of the sentence such as: this is a {big / large} house. But even if two words are interchangeable in some sentences, there may still be differences in meaning, so that there is an important question in lexical semantics, which presents itself to us, is whether total or strict synonym exists in a language or whether there is always a difference between words.
As I mentioned above that synonyms are any two words having the same meaning, and according to Alan Cruse (2006) definition of absolute synonyms "Words would be absolute synonyms if there were no contexts in which substituting one for the other had any semantic effect". That means we can use these synonyms in contexts since these synonyms are identical and share same semantic features. Unfortunately, synonyms can't be applied in all contexts, and perhaps, there is no as an absolute synonym for any word, because it is right that some synonyms used in some contexts, but not all. There are some factors which control and prevent the identification of synonyms in most circumstances and contexts. So that synonymy becomes one of the modern linguistics' most controversial problems. The duality of synonyms is their most confusing feature. They are somewhat the same and yet they are obviously different, even though synonyms are based on the similarity between words, there are still some problems in using synonyms.
According to Lyons (1981: 148) distinguishes between two kinds of synonymy in the strict sense, complete and absolute synonymy. He defines them as follows: "…lexemes can be said to be completely synonymous (in a certain range of contexts) if and only if they have the same descriptive, expressive and social meaning (in the range of contexts in questions). They may be described as absolutely synonymous if and only if they have the same distribution and are completely synonymous in all their meanings and in all their contexts of occurrence." Here he says that complete synonymy is rare, and absolute synonymy hardly exists. Murphy (2003) also stated that Words can be s similar in two ways. They are more similar if they share more characteristics in common (having the same denotation, connotation, register, etc.), or they are more similar because they match more closely on any one of these features - all others being equal or all others being ignored.
However, given that a basic function of words is to be semantically unique, it is not surprising that such identical pairs are rare. That being so, the problem of characterizing synonymy is one of specifying what kind and degree of semantic difference is permitted. One possibility is to define synonymy as 'propositional synonymy': two words A and B are synonyms if substituting either one for the other in an utterance has no effect on the propositional meaning (i.e. truth conditions) of the utterance. This is the case with, for instance, begin: commence and false: untrue (on the relevant readings):
The concert began/commenced with Beethoven's Egmont Overture.
What he told me was false / untrue.
While this is a convenient and easily applied way of defining synonymy, it does not capture the way the notion is used by, for instance, lexicographers, in the compilation of dictionaries of synonyms or in the assembly of groups of words for information on 'synonym discrimination'. Alan Cruse (2006) stated that some of the words (withhold: detain; joyful: cheerful; heighten: enhance; injure: damage; idle: inert: passive) are propositional synonyms, but others are not, and for these we need some such notion as 'near synonymy'. This is not easy to define, but near-synonyms must share the same core meaning and must not have the primary function of contrasting with one another in their most typical contexts. For more clarification, it is better to take this example: collie and spaniel share much of their meaning, but they contrast in their most typical contexts.
In addition, sometimes differences between the usages of synonyms are a matter of stylistic characteristics; because the words in all are divided to formal words which are restricted to formal situations, and Informal words are divided into three types: colloquial, slang, dialect words. Even though some formal words carry the same meaning of informal words, we still can't use them in informal situations, this will conversation more boring such as: the verbs commence and receive are usually used in formal styles than begin and get. So that if someone said to his friends at party dinner "let us commence dinner" would be seen oddly over- formal. Similarly, we received the news yesterday would probably be restricted to formal contexts.
Another important element in meaning is evaluative or emotional overtones a word may have which would fall within the scope of expressive and social meanings is the connotation of lexemes. According to Murphy, (2003) connotation definition is that "It involves associations that do not directly affect the conditions on reference, but which may give some slant to the description". That means the connotation of a word is the set of ideas associated with it in addition to its explicit meaning, and the connotation of a word can be personal, based on individual experiences. According to Lyons, (1981) association between words or phrases, which is distinctive about their typical contexts of occurrence, can be created by the frequent use of a word or phrase in one range of context rather than another. For example, the verbs kill, murder, assassinate, and execute. Although all these words share same meaning of take away life, they are clearly not total synonyms. Murder has elements of meaning which kill doesn't have; it implies a motive and premeditation, and most think immediately of crime of violence. Assassinate also implies a motive, but usually an impersonal one. Many speakers think of politically motivated killing. Execute is used in legal context and follows a socially sectioned sentence of death. So that all of these words are synonyms and share same meaning of take away life, but they each have different connotations.
In addition, there are differences in connotations between two words although the pairs can be used as synonyms, because the speakers use them to show positive or negative meanings and approval or disapproval. For example, the word fascist is commonly applied not to members of the 'Fascist Party' but to condemn or even insult people who have particular political view or social attitudes. Freedom- fighter and terrorist have very different connotations. Generally the speaker will refer to a group which is taking direct action in support of a cause which the speaker himself supports as freedom- fighter. The label terrorist is used to condemn actions.
