Definition of valency in US English:



  • another term for valence
    • ‘The higher the valency of the counterions, the more significant is the reversal of the effective charge of the aggregates.’
    • ‘Depending on the charges of additional groups that may be bound to the phosphate group, phospholipids in water can have a valency between - 2 and + 1, and also neutral groups are possible.’
    • ‘The degree of flocculation, and hence randomness of particle orientations on sedimentation, generally increases with the concentration and valency of the cations in the solution.’
    • ‘It is well-known that aggregation can be induced by changes in pH, the salt concentration, valency of ions, or the polarity of the solvent.’
    • ‘Plutonium has five different crystal-type conditions or ‘phases’ that it can be in, and has five possible valencies.’


Early 17th century: from late Latin valentia ‘power, competence’, from valere ‘be well or strong’.