A word or a phrase that is informal and particular to certain time periods or social situations is called:

Colloquialisms

Explanation:

Colloquialism is the use of informal language in certain time periods or social situations. In colloquialism we find slang words, foreign words, neologisms, and abbreviations.

in the quotation from passage, connie willis states that literature is a way for authors from the past to communicate with readers of today. we can read their stories, books, and other texts to learn lessons about life. willis refers to these lessons as messages “from beyond the grave.” willis has a favorable viewpoint about the timelessness of literature.