It's important to provide the full context in these cases.
I found it on http://www.hiphoparchive.org/hiphop-lx/higher-learning
Meaning - a notion in semantics classically defined as having two components: Reference, anything in the referential realm denoted by a word or expression, and Sense, the system of paradigmatic and syntagmatic relationships between a lexical unit and other lexical units in a language.
The term 'sense' is used in at least 2 (related but distinct) ways in linguistics. One in lexicography, it's simply used to refer to one of the 'meanings' listed under a lexical items.
The second comes from the Fregean tradition of distinguishing between reference (the thing the word denotes, refers to, points to) and sense (what makes the reference meaningful in the context of a proposition - I'm being very liberal here).
One synonym for sense is connotation. And from this perspective, the definition makes sense. Connotation can be thought of as a result of comparison to similar words (paradigmatic relationships) and contexts of use (syntagmatic relationships).
Of course, nobody reading the definition without the headword would guess that that's what it was referring to. In the structuralist tradition that would simply be a definition of grammar (as @jlawler points out).