Synonyms for Formative:

adj.

beginning (adjective)
starting, sprouting, baby, primeval, hatching, budding, Commencing, introductory, preliminary, early, beginning, infantile, Dawned, inaugural, embryonic, primal, initial, nascent, original, preparatory, germinal, new, genesis, foremost, alpha, incipient, precursory, first, infant, maiden, primordial, fetal, newborn, emerging, aboriginal.
causative (adjective)
generative, causative, causal, executive, motivational, pivotal, effective, germinal, influential, responsible.
influential, impressionable (adjective)
shaping, immature.
juvenile (adjective)
infant.
original (adjective)
generative, causal.
pure (adjective)
stark, clean, uncluttered, faultless, spotless, monolithic, austere, atomic, white, virtuous, unblemished, aboriginal, immaculate, basal, unsullied, foundational, clear, pure, honorable, guiltless, indivisible, simple, elementary, primary, angelic, prime, untainted, innocent, untarnished, chaste, undefiled, undiluted, decent, plain, sinless, purebred, blameless, unalloyed, unadorned, unadulterated, bare, stainless, fundamental, essential, basic, primal, irreducible, nascent, elemental, Simon-pure.
young (adjective)
juvenile.

n.

driving, juvenile, enabling, deciding, decisive, pliable, impressionable, instrumental. formative (noun)
shaping, immature, young, constructive, inchoative.

Other synonyms:

driving, deciding. enabling, decisive. instrumental. Other relevant words:
impressionable, decisive, constructive, immature, juvenile, pliable, enabling, young, inchoative, shaping.

Usage examples for formative

  1. More specifically, it is a portion of plastic, organized substance, functioning as an individual and containing potentially an elemental organ plus a formative power. – A Mechanico-Physiological Theory of Organic Evolution by Carl Von Nägeli
  2. Society in its formative state needs, above all other agencies, the salutary influences of religion. – Thirty Years in the Itinerancy by Wesson Gage Miller