By bidirectional I mean, if word A is synonymous with word B, does it follow that word B is always synonymous with word A? Are there any common exceptions to this rule?

Extending this - if word A is synonymous with word B, and word B is synonymous with word C, word C may or may not be synonymous with word A?

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    Synonyms only exist in context. So "always synonymous" makes no sense. And your extension, again, is possible for some words in some contexts, but not for other words in other contexts.
    – RegDwigнt
    Oct 26, 2012 at 11:46
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    So I guess, as with most things - sweeping generalizations are always wrong!
    – MattDavey
    Oct 26, 2012 at 11:46
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    Pretty much if one word appears on synonyms list of another, the other will appear on the list of the first. But depending on the word, word A may be always a synonym of word B, while B is a synonym of A only in specific contexts.
    – SF.
    Oct 26, 2012 at 12:34
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    To extend @RegDwighт's comment, yes, -in- a given context, the relation is bidirectional. But it allows one to pursue faulty arguments by switching contexts implicitly. A pole is a post, but a post is a letter, therefore people from Poland are sealed in envelopes.
    – Mitch
    Oct 26, 2012 at 13:00
  • Synonyms exist in context. But in the context in which they are synonyms, the relationship is symmetric. In a broadened context, or a different context, it might not be (so they are not synonyms).
    – Kaz
    Oct 26, 2012 at 18:02

4 Answers 4


Perfect synonyms are equivalent, which means that all you say in your answer is true for them. But perfect synonyms are really unusual; some people say they don't exist at all.

In reality, synonyms are usually just partial, which means that they share a common meaning in some circumstances, but not in all of them. So the symmetric property (if A is a synonym of B, B is a synonym of A) holds true, but not the transitive (if A is a synonym of B and B is a synonym of C, A is a synonym of C).

Example: lead is a synonym of main (lead actor = main actor), graphite (in a pencil) or conductor (in electricity), but these words are not synonyms between them at all.

  • Perfect synonyms only exist when they are related to death: dead, deceased, dead body, corpse. In Spanish and French is the same thing.
    – k-dev
    Oct 26, 2012 at 14:35
  • @k-dev I don't think those are perfect synonyms. Further, I think there are perfect synonyms unrelated to death (e.g. sofa and couch). Oct 26, 2012 at 16:53
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    @k-dev "My computer just died." is perfectly valid in English, but it doesn't leave a corpse, nor is it deceased.
    – Izkata
    Oct 26, 2012 at 16:55
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    @Zano Ideas can gestate as well, but they can't be knocked-up as far as I know.. ;)
    – Izkata
    Oct 26, 2012 at 17:00
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    @UncleZeiv: I intentionally used this example because I think it is clearer. In any case, the conclusion is the same: synonyms do not generally form clusters.
    – Gorpik
    Oct 28, 2012 at 15:22

Part of the difficulty is what we mean by synonym. When we use reference works to search for synonyms, we are usually presented with a variety of choices. The Collins Thesaurus (found here) lists the following synonyms for the word pistol

  • handgun
  • shooter
  • piece (U.S. & Canad. informal)
  • automatic
  • revolver
  • side arm

Not all pistols are revolvers. Not all pistols are automatics. Revolvers are not automatics.

Very often a term that is either a subset or a superset of another term is considered a synonym in many contexts. One could argue that such offerings are not true synonyms, but in practice we may not make that distinction.

The very fact that we seek synonyms to words indicates that there are subtle differences between the word we know and the word we seek. If not, we would always use the original (except perhaps to avoid boredom or for euphony).

For beauty, the following are listed

attractiveness, appeal, charm, grace, bloom, glamour, fairness, elegance, symmetry (formal or literary), allure, loveliness, prettiness, seductiveness, gorgeousness, pleasantness, handsomeness, pulchritude, winsomeness, comeliness, exquisiteness, seemliness, pleasingness, prepossessingness

Some of these terms do seem to be true synonyms, but create different impressions or may be used in different contexts. Words that are listed as synonyms often have connotations that better suit a given context. While their denotation may be roughly equivalent or even identical, their shades of meaning are not.


Synonyms are words that sometimes have the same meaning, so they overlap. Even if A sometimes = B and B sometimes = C, that doesn't mean that A sometimes = C. See the 3-circle Venn diagram here.


You can think of two words like of tho sets of possible meaning (including denotation, connotation, contextual peculiarities, etc., etc.)

Thus, speaking of word comparison, we actually are speaking about set relations. Above-mentioned Venn diagram are nice visualisation of how actually sets can overlap.

So, no, not all synonyms are "bidirectional" - in mathematics this called bijective, or one-to-one correspondence.

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