So
“So” is best known as an adverb, but it can also be seen in the role of a conjunction. In the question of so versus such, remember that “so” can never be used as an adjective. If the word being described is a noun or pronoun, “so” cannot be used, as it can only modify adjectives and other adverbs.
1. To a great degree, or “very.”
“The Reilly family is so friendly.”
“Mary is so silly. Look at that hat she is wearing.”
2. In the manner or way shown or described, often teamed with the word “just.”
“Clean these glasses so, then stack them so.”
“He placed his hands behind his head, just so.”
3. In the previously-mentioned condition or state.
“The school is run down and has long been so.”
“The bridge was out last night and likely remains so.”
4. To an extent indicated.
“She wishes he didn’t drive so fast.”
“Don’t look so sad, tomorrow is your birthday.”
As a final illustration of the “so versus such” issue, let us return to lovely Bertha. “Such” describes a noun in the original sentence.
“Bertha was such a beauty that her father would sit on the porch each night with a baseball bat.”
The noun can be swapped out for an adjective to accommodate the word “so.”
“Bertha was so beautiful that her father would sit on the porch each night with a baseball bat.”
The words such and so are also part of various English idioms, some of which seem at first to bend or even break the rules