Idea, concept, conception, thought, notion, impression mean what exists in the mind as a representation of something that it apprehends or comprehends or as a formulation of an opinion, a plan, or a design.
Idea is the most comprehensive and widely applicable of these terms; it may be used of an image of something at one time or another actually perceived through the senses, or of something never perceived but visualized from bits of information or of something that is the clearly or vaguely defined product of fancy, imagination, or inventive power.
It may denote a mere supposition or a good or practical solution or suggestion or a ridiculous or preposterous suggestion.
Concept applies in logic to the idea of a thing which the mind conceives after knowing many instances of the category to which it belongs and which is devoid of all details except those that are typical or generic. In more general use the term applies to a formulated and widely accepted idea of what a thing should be.
Conception is often used in place of concept in this latter sense; in fact it is sometimes preferred by those who wish to keep concept as a technical term of logic. However conception so strongly suggests the activity of the mental power of bringing into existence an idea of something not yet realized or not yet given outward form that it often implies not only the exercise of the reflective powers but of the imagination as colored by feeling; the term therefore more often applies to a peculiar or an individual idea than to one held by men as a whole or by an entire class, profession, or group.
Conception is also, especially in literary and art criticism, the usual term for the idea or design conceived by the writer or artist in advance of or in company with his giving it expression or form.
Thought applies either to an expressed or to an unexpressed idea, especially one that comes into the mind as a result of meditation, reasoning, or contemplation.
Notion often adds to idea’s implication of vagueness the suggestion of caprice or whim or of half-formed or tentative purpose or intention, but notion may also come close to concept in suggesting a general or universal concept or to conception in denoting the meaning content assigned by the mind to a term.
Impression (see also IMPRESSION 1 ) usually suggests an idea which comes into the mind as the result of an external stimulus.