Admittedly, there is no such thing as perfect synonymy, but the meanings of many pairs of words are close enough for this term to be used in the context of a pastime like crosswords.
( ( ( ( ( Admittedly ( , ( there ( is ( ( no ( such thing ) ) ( as ( perfect synonymy ) ) ) ) ) ) ) , ) but ) ( ( ( the meanings ) ( of ( ( many pairs ) ( of words ) ) ) ) ( are ( close ( enough ( for ( this ( term ( to ( be ( used ( in ( ( the context ) ( of ( ( a pastime ) ( like crosswords ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (ADVP (RB Admittedly)) (, ,) (NP (EX there)) (VP (VBZ is) (NP (NP (DT no) (JJ such) (NN thing)) (PP (IN as) (NP (JJ perfect) (NN synonymy)))))) (, ,) (CC but) (S (NP (NP (DT the) (NNS meanings)) (PP (IN of) (NP (NP (JJ many) (NNS pairs)) (PP (IN of) (NP (NNS words)))))) (VP (VBP are) (ADJP (RB close) (JJ enough) (PP (IN for) (NP (DT this) (NN term) (S (VP (TO to) (VP (VB be) (VP (VBN used) (PP (IN in) (NP (NP (DT the) (NN context)) (PP (IN of) (NP (NP (DT a) (NN pastime)) (PP (IN like) (NP (NNS crosswords)))))))))))))))) (. .)))
Synonymy is imperfect, but close enough for it to be used for entertainment purposes.
( Synonymy ( ( is ( ( ( imperfect , ) but ) ( close ( ( enough ( for it ) ) ( to ( be ( used ( for ( entertainment purposes ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Synonymy)) (VP (VBZ is) (ADJP (ADJP (JJ imperfect)) (, ,) (CC but) (ADJP (RB close) (RB enough) (PP (IN for) (NP (PRP it))) (S (VP (TO to) (VP (VB be) (VP (VBN used) (PP (IN for) (NP (NN entertainment) (NNS purposes)))))))))) (. .)))