The Oxford Thesaurus An A-Z Dictionary of Synonyms INTRO ...

of the words given as synonyms without any adjustment of the
grammar or phrasing of the example. That is not to suggest that
the synonyms are identical: 'permeable' and 'pervious' belong to a
different register from that of 'spongy, spongelike', being more
common in technical usage. Some might argue that 'penetrable' is
not synonymous with the other listed words; but it is the function
of this book to provide synonyms for the main entries, not for the
other synonyms that might be listed. No claim is made--nor could
it be made--that synonyms are identical, either to one another or
to another word, merely that they fall well within the criteria of
what, for practical purposes, is viewed as synonymy in the
language.
It is certainly true that substituting for porous any of the five
listed synonyms will yield five standard English sentence.
b. Some judgement is required of the user in determining the syntax
and idiomaticity with which a given word or expression can be
substituted in an illustrative context: words are rarely as
readily interchangeable in a context as might be components in a
chemical or mathematical formula. Moreover, while such formulae
are reflective of science, language offers its users the virtually
infinite variety available only in art, with each individual
speaker of any language being presented with the opportunity to
become an artist.
In the following example, nearly all terms can be substituted for
adjoining in the first illustrative sentence; to create idiomatic
parallels to the second sentence, the parenthetical prepositions
must be used:
adjoining adj. neighboring, contiguous (to), adjacent
(to), abutting, bordering, next (to): We have bought the
adjoining land and will build our new house there. The
land adjoining the supermarket is for sale.
Interpreting this, the following are all idiomatic: adjoining
land, neighbouring land, contiguous land, adjacent land, abutting
land, and bordering land. But if the context requires the
adjective to come after land (with a following noun), then the
parenthetical words must be added to yield constructions that are
idiomatic, like land adjoining the supermarket, land neighboring
the supermarket, land continuous to the supermarket, land adjacent