Why this term exists
A connection is not yet a meaningful relation. Two things can be linked, correlated or similar without the link changing what either can do. Relatio names the relation at the point where difference becomes consequential.
Definition in the system
Within Semonika, Relatio is primary. Meaning is not treated as an isolated substance located inside one object and later transmitted to another. Meaning happens through the relation that makes a difference matter.
Relatio does not require similarity. Similarity is one possible mode of relation; complementarity is another. Reciprocity, opposition, coupling, dependence, feedback and temporal coordination can also form meaningful relations. The question is not “how alike are A and B?” but “what can the relation between A and B make possible, constrain or change?”
This is why the framework can describe both resonance between similar patterns and co-adaptation between unlike but complementary systems without forcing both into a single similarity metric.
Example
Bee ⇄ flower. Their forms are not copies. Their differences fit into a reciprocal ecological relation, so each becomes part of the selection environment of the other.