Meaning of Coupling in Modelling
In Earth-system models, the term "coupling" is often used in two ways.  The first is "offline" coupling, where output from one model is passed to another model for computation of some variable.  The second is "online" coupling, where the feedbacks are allowed to pass between the two models.  Online coupling is synonymous with "fully coupled".  

A good example is when wildfires are modeled with coupled meteorology-chemistry models.  Historically, the aerosol emissions from the fire would be modeled by a separate chemistry model that only used the meteorology model as an input (e.g. offline coupling).  However, now you can fully couple (e.g. online coupling) the chemistry with the weather such that the heat and aerosol released from the fire perturbs the meteorological/radiation calculations in the next iterated time step.