As rshdunlop mentioned I was not after a definition (having studied latin for 8 years and having had a past interest in photography and set lightning), but a clarification on the context of word.
What do YOU mean by it? Do you mean that words convey a shadow of various levels of darkness based on the angle one chose to experience them from, the varying level of darkness being used here to convey that people get different emotional responses to the particular word?
So if I understand you find the word "Poo" irritating because to you it is a misspelling of a childish term used in an adult discussion context (wrong word / wrong context).
Well I actually understand what you mean. When a language is rich enough to have various alternatives why limit yourself to a safe, slightly mutted word (because child terms are always less offensive and make you feel safer)?
It is a question of priority though: conveying a message quickly, a preference for more mutted words and at the end a personal choice.