outward vs tip of the iceberg

outward

adv
  • Towards the outside; away from the centre. 

adj
  • visible, noticeable 

  • outer; located towards the outside 

  • Tending to the exterior or outside. 

noun
  • A ward in a detached building connected with a hospital. 

tip of the iceberg

noun
  • A small indication of a larger possibility; the first part encountered of a problem that is much bigger than it seems. 

How often have the words outward and tip of the iceberg occurred in a corpus of books? (source: Google Ngram Viewer )