The line between plesionymy and cognitive synonymy can be drawn with some precision. However, the limits of plesionymy in the opposite direction along the scale of synonymity are more difficult to specify; as the semantic distance between between lexical items increases, plesionymy shades imperceptibly into non-synonymy.
Source: wiktionary
Indeed an analysis in which the semantics of plesionymy (near but peculiar synonymy) can be traced through the text (see Stockwell 2000) serves only to increase the appreciation of the poetic mechanics of paranoia and disturbance in the text.
Source: wiktionary
Essentially, the repeated syntactic form motivates a cognitive search for plesionymy, and a reader is forced upwards on a granularity scale until a domain is found that is plausibly common to the two elements of the plesionym.
Source: wiktionary