Scrabble?! ISOTONICITY

Definitions of ISOTONICITY in various dictionaries:

Tonicity is a measure of the effective osmotic pressure gradient, as defined by the water potential of two solutions separated by a semipermeable membrane. In other words, tonicity is the relative concentration of solutes dissolved in solution which determine the direction and extent of diffusion. It is commonly used when describing the response of cells immersed in an external solution. Unlike osmotic pressure, tonicity is influenced only by solutes that cannot cross the membrane, as only these exert an effective osmotic pressure. Solutes able to freely cross the membrane do not affect tonicity because they will always be in equal concentrations on both sides of the membrane. It is also a factor affecting imbibition. There are three classifications of tonicity that one solution can have relative to another: hypertonic, hypotonic, and isotonic.