Thought means a concept or judgment, on the one hand (e.g., the thought of one's own death), or the act of thinking, on the other. The activity is associated with understanding, meaning, creativity, reasoning, and learning; cognition is a close cognate. It can also mean the body of published thoughts of a particular person, as in "Plato's thought."
The reader is directed to the articles on the above topics, but on this page it would be appropriate to explore the relationship between so-called objects of thought, meaning such things as concepts or judgments, and the process of thinking. The German philosophers Franz Brentano and Edmund Husserl are famous for saying that conscious thinking is intentional, that is, it has an "aboutness." In other words, we cannot think without thinking about something or other; that about which we think is often called the "object" of thought (where the thinker is called the "subject"). Philosophers sometimes describe the "objects" of thinking not as external objects, like rocks and trees, but as internal stand-ins, like ideas of rocks and trees. If, for example, Socrates is thinking about courage, we often say that he is talking about something mental or abstract—a concept, idea, or the Form of courage—rather than the particular courage of a particular person. In the same way, Socrates might "entertain a thought" that he is mortal, and while we might say that Socrates is thinking about the particular fact that he is mortal, sometimes we say that what he is thinking about is, again, something abstract or mental—a proposition or a judgment.
It is confusing to puzzle out what thinking is "about," and this is deeply associated with both some of the most intractable problems in philosophy, from three different branches: metaphysics (the problem of universals), philosophy of language (the meaning of meaning), and philosophy of mind (the nature and objects of consciousness).
It is surely apt that the concept of thought is, indeed, so thought-provoking.
In the English language, a number of popular phrases evoke thought: