"Words" - not commonly used that I came across while reading papers

Caveat - Warning / Caution / an explanation
Example :
A final Caveat : Keep out
One caveat for the wide acceptance of IP is its simplicity.

morbid - unhealthy mental state / horrifying
Example:
morbid curiosity
morbid details of the murder

gainsay - deny / declare false / oppose
Example:
The social importance of immunology cannot be gainsaid.