The first of the four considerations that enter into word choice, according to John Ciardi and Miller Williams' How Does a Poem Mean? (1959), is: "A word is a feeling". The main point here is that there is an emotional component in a word, its "connotation", as opposed to its literal meaning (i.e. dictionary definition) or "denotation". Thus, the word choice informs the reader about the attitude (or tone) of the writer, or speaker, in the case of drama. Let's take an example from King Lear. In act four, scene one Goneril (the daughter who swore her great love to him in the first scene) is in the process of starting a conflict with with the king, and as she accurately deduces, the best way to do so is to attempt to remove some of his royal trappings, in this case the hundred knights who follow him. And she also realizes that to take a formal and patronizing tone will help with it as well. Here is part of her lecture:

I do beseech you

To understand my purposes aright.

As you are old and reverend, you should be wise.

Here do you keep a hundred knights and squires;

Men so disorder'd, so debosh'd, and bold

That this our court, infected with their manners,

Shows like a riotous inn. Epicurism and lust

Make it more like a tavern or a brothel

Than a grac'd palace. The shame itself doth speak

For instant remedy. Be then desir'd

By her that else will take the thing she begs

A little to disquantity your train,

And the remainder that shall still depend

To be such men as may besort your age,

Which know themselves, and you.

Note the condescending and distant (almost chilling) tone and how almost every word is calculated to achieve maximum emotional impact. "A word is a feeling" indeed.