General nouns referring to ideas

a regularly repeated arrangement

specific subjects that someone discusses or writes about

amount or level

a typical quality that something has

basic idea or rule that explains how something happens or works]

statement of the rules on which a subject of study is based or, more generally, an opinion or explanation

one individual part of a situation, problem, subject

description of a system or process which explains how it works

basic character of something

important subject or problem

thing which is being discussed, considered or studied

main subject of a talk, book