Take Aback Meaning

(nautical, usually passive) Of a ship: to catch it with the sails aback suddenly.

Example:   I was rather taken aback by his angry reply.
  The bad news took us aback.
2014, Steve Rose, "Dawn of the Planet of the Apes: a primate scream - first look review", The Guardian, 1 July 2014:
  They haven't seen humans for years, so when a small expedition, led by Jason Clarke, stumbles into apetopia, both sides are taken aback.