I was expecting an discernible relation to osmosis. Didn’t see that in the definition.
Osmolarity is the measure of solute concentration, defined as the number of osmoles (Osm) of solute per liter (L) of solution (osmol/L or Osm/L).
Osmolality is a measure of the osmoles of solute per kilogram of solvent (osmol/kg or Osm/kg).