Metaphor and Metonymy

The metaphor and the metonymy are both figures of speech where one word is used to refer to something else. There are few Klingon words that can be used metaphorically or as a metonymy. The topic was never addressed per se in canon literature, but KGT mentions one metaphorically used word and one metonymy.

The difference between these is:

a metaphor compares something, like when Shakespeare said that "the world is a stage".(1)
a metonymy is used as a replacement for something, such as "Hollywood" refers to American movies even if not all are produced exactly in Hollywood itself; Another examples is being "loyal to the Crown" where the crown stands for the King or the government.
In KGT, Okrand explained metonymy as "whereby one word (or phrase) stands for another with which it is associated." (2)

Metaphor

nuH – In the phrase Hoch nuH qel, literally "consider every weapon", the word nuH weapon is used metaphorically for possibility (which is regularly DuH). This is based on the similar sounding pronunciation of n and D in the Krotmag dialect. (3)
'enDeq means bladder and is a part of anatomy, but it can be used metaphorically in other contexts, which is the way it works in English. (4)
Soj food is used in its idiomatic sense of "matter, concern, affair", as in the phrase tlhIngan Soj 'oH. not bIyaj "That's a Klingon matter — you'll never understand." (5)
Sor is a verb and means "speak non-metaphorically".

Metonym

There is only one word clearly defined as a metonym: ngup cape can be used to refer to a person in a position with power. This is based on the fact that the leader of the Klingon High Council typically wears a ceremonial cape. (6)