Words from
acuity
    sharpness or keenness of thought, vision, or hearing.
    
    Source: Children of Time - Novel by Adrian Tchaikovsky
    
    
      I really like this word. I write it down pretty much every time I see it.
    
    
  ersatz
    (of a product) made or used as a substitute, typically an inferior one, for something else.
    
    Source: Children of Time - Novel by Adrian Tchaikovsky
    
    Usage Example: e.g. ersatz coffee
    
  riposte
    a quick clever reply to an insult or criticism.
    
    Source: Children of Time - Novel by Adrian Tchaikovsky
    
    
      Comes from fencing.