adjective (a)

• easily impressed or influenced(adj.all)

  Example:
  An impressionable youngster.
  An impressionable age.
  

  Synonym:
  impressible, waxy
  Antonym:
  unimpressionable
  

  source: wordnet30
• Liable or subject to impression; capable of being molded; susceptible; impressible.(adjective)

  source: webster1913