When people argue about the definition or meaning of a word. This usually starts in the middle of an argument and distracts from the main topic of the argument. Whether done intentionally or not depends on the people arguing.
When an argument deteriorates and its focus becomes one about word
definitions rather than the main topic, a person will usually say "Oh, now we're just arguing
semantics". Usually by this point, the arguement has become a
waste of time because it has morphed into a bunch of bickering about irrelevant, unimportant details rather than the original main point.
If someone accuses you of arguing semantics, they're usually accusing you of intentionally avoiding the topic. In this case, the person may or may not be misusing the phrase in order to do so. If you're not actually arguing about word
definitions, then they should accuse you of being nit-picky instead (as that would be more accurate) but to explain it to this degree becomes a bit nit-picky in and of itself and so for obvious reasons, this is the end.
Jenny: Hey Tommy, did you
do your homework?
Tommy: I would never do my homework.
Jenny:
What do you mean? You always
do your homework!
Tommy: No, I would never "do" my homework - that would be gross. But if you want to know if I completed my homework...
Jenny: Oh, please. Spare me. Now you're just arguing semantics.
