From Longman Dictionary of Contemporary Englishformativefor‧ma‧tive /ˈfɔːmətɪv $ ˈfɔːr-/ adjective [only before noun] SSEFFECT/INFLUENCEhaving an important influence on the way someone or something developsformative years/period/stages etc (=the period when someone’s character develops) He exposed his children to music throughout their formative years.formative influence/effect etc International politics were a formative influence on the party.
Examples from the Corpus
formative• Assessment for selection and evaluation is summative; assessment to inform the teaching is formative.• The Marines were a formative experience for Bernie.• For many, these works recall childhood memories; they were the silent witnesses to countless formative experiences.• At the same time, the experience was formative in a more immediately practical way.• I learned a great deal during that formative period about what made people tick and one saw what life was really like.• According to Aristotle, the male semen provides the formative power that shapes the foetus, mentally and physically.• The plan is still in a formative stage.• The formative years of a genius are a perennially fascinating and tantalising subject.• The formative years of many of the elderly who were surveyed was a ti-me of popular demand for greater equality.• It must have been a considerable advantage when faced with the numerous moves the children had to make in their formative years.formative influence/effect etc• His formative influence as a boy had been John Cassell's Popular Educator, first published in 1852. 