formative
1. for.ma.tive \'fo.r-m*t-iv\ aj 1a: giving or capable of giving form : CONSTRUCTIVE {a ~ i nfluence} of an affix or other word element 1b: used in word formation or inflection 2: capable of alteration by growth and development; also : produci ng new cells and tissues 3: of, relating to, or characterized by formative effects or formation { ~ years} - for.ma.tive.ly av 2. formative n : the element in a word that serves to give the word appropriate form and is not part of the base