Vocabulary for writing about an author's use of language:
Diction is the choice and use of words.
Tone is the sense of a writer's attitude toward self, subject, and readers. Tone is revealed by words and sentence structure as well as by content.

Types Of Language

Emotionally Charged Language is language that affects perceptions. Emotive language is designed to elicit certain feelings from the reader.

Questions to ask: Is the language emotionally charged? How does it affect the reader? What emotion does the reader experience? Why?

Connotative Language a word may also carry an association with one or more feelings that shape the reader's response to it. We call these associations the connotations of the word. Thus, a word may take on a meaning quite different from its dictionary meaning (denotation).

Questions to ask: How do the connotations of the word sway the reader's opinion? What other word(s) might the writer have used? Why? How does this connotation serve the writer's agenda?

Slanting is the practice of selecting facts or words with connotations that favor the arguer's bias and discredit alternatives.

Question to ask: Does the writer's choice of words betray his or her bias or special interest?

Picturesque Language can create images. Such words convey a writer's thoughts, feelings, and experiences.

Questions to ask: What images does the writer create with words? Do the picturesque words strengthen or detract from the argument?

Intensifying is a strategy a writer uses to focus on or draw attention to anything that would make his or her case seem stronger and the opponent's case seem weaker.

Downplaying is a strategy used to dismiss or divert attention from weak points or from points that would make an opponent's case look good.

Questions to ask: Which words are intensified? Downplayed? (Look for adjectives.) What effect does this have on the reader?

Abstract words name qualities and ideas.

Concrete words name things we can know by our five senses of sight, hearing, touch taste, and smell. (Concrete details are often used to create images.)

Questions to ask: Does the writer use abstractions? Does the writer assume the reader agrees with his or her definition of the term? How does that assumption strengthen or weaken the argument?

Figurative Language (figures of speech) - These expressions suggest meanings different from their literal meaning in order to achieve special effects.

A metaphor is an implied comparison between two unlike things.

A simile is an explicit comparison, using like or as, between two unlike things.

Questions to ask: Do the metaphors or similes help the reader understand the claims the writer is making? How?

A euphemism is a pleasant or flattering expression used in place of one that seems disagreeable.

Slang consists of expressions used by members of a group to create bonds and often exclude others.

Jargon is the specialized language of a group (usually a professional group).

A slogan is an attention-getting expression used in politics or advertising to gain support for a cause or product.

A cliché is a worn-out expression or idea.

Sources:
Fowler, H. Ramsey and Jane E. Aaron. The Little, Brown Handbook. Fifth Edition. New York: Harper Collins, 1992.
Hirschberg, Stuart. Strategies of Argument. Boston: Allyn & Bacon, 1996.
Rottenberg, Annette T. The Structure of Argument. Boston: Bedford Books, 1997.