Situation of imbalance in which the level or type of skills available does not correspond to labour market needs.
Source: CEDEFOP 2014, Europe

Situation in the labour market where the level of skills of individuals does not match the level of skills required in the jobs (see Gap, Overskilling, Underskilling, Overqualification, Underqualification). Mismatches could be vertical (when the level of skills or education is more or less than the level of skills or education required to perform a job), horizontal (when the type of education or skills is not appropriate for the current job, but the level of education or skills matches the requirements of the job) or geographical (where the workers with types and levels of skills or education required are based in a country or region different from where such skills are needed).
Source: EU commission (Skills panorama) 2015, Europe

Skills mismatch is an encompassing term which refers to various types of imbalances between skills offered and skills needed in the world of work. [...]
Vertical mismatch: The level of education or qualification is less or more than required.
Horizontal mismatch: The type/field of education or skills is inappropriate for the job.
Source: ILO (STATS) 2014, Europe

A situation where there is a (qualitative) discrepancy between the qualifications and skills that individuals possess and those that are needed by the labour market.
Source: CEDEFOP 2015, Europe