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.