"Words are Hard"

This is the phrase that one of my mission companions would always say when either of us stumbled over our words.
This week I came across two different words that are commonly used but still used vaguely (at least I use them vaguely). It makes it difficult to communicate ideas when you and your audience may not understand a word in the same way.
First: Exactness
In the LDS church people often talk about obeying commandments (and rules) with exactness. I have never particularly liked the phrase I always read it with exactness being synonymous with perfectness, which is just humanly impossible (and God does not ask the impossible) Then, this week someone said that obeying with exactness meant there was no gray in life, only black and white... and nice(?) as that thought is I just don't see the world as black and white.... So I looked up exactness on google. It reads "the quality of being accurate or correct; precision." Which as you may notice says nothing about perfect.... I looked at another article about accuracy and precision. In my words accurate means being correct while precision means consistent. And I think I can obey with correctness and consistency even when I can't obey with perfection. The best thing about the above mentioned article, at least for my purposes is the image showing what accuracy and precision looks like when you are shooting at a target. Notice how even with high accuracy and precision the shots are not all dead center. So, I guess I have no problem with the phrase obey with exactness anymore... I just had to look up the word I though I knew.
Second: Mature
A group of my geology friends were talking about which of us was the most mature. One girl was nominated as the most mature (even though she is the youngest of us), but then I got wondering if we were just judging on who the most controlling person was. This one was a little trickier to find the right definition (we were obviously talking about physical maturity or the maturity of an industry). But I found this definition on the Merriam-Webster online dictionary "having of showing the mental and emotional qualities of an adult." I think that is roughly what we were all thinking of for as the definition of mature.... but it is still a vague term. I mean does that mean we should have been judging on the adeptness of planning out our lives and jobs, or the ability to control our stress in appropriate ways, or being consistently reliable in what we say we will do... I have no idea... I guess that one we would have to define for the moment.
Sometimes I am just floored that communication is possible at all with how messy and imperfect words (and nonverbal communication) are.