Quality as a high political priority all over the world has to do with control over educational output in relation to decentralization and autonomy of schools. In the article, the concept of quality is analysed both in relation to original etymological meanings and the imbedded implications, and by empirical semantics as regards the present use of language and operational definitions in quality assurance practice. Findings: Original meanings can be characterized as a horizontal focus of difference in kind, classification and descriptions of properties and characteristics of objects, persons and processes. Practical and operational use of the term is vertical, attributing value and judging and it is based on matching between outcome of activity and criteria to be met. Common definitions of the quality in judgment is fitness for use or fitness for purpose.