Conception, n.
Etymology: [F. conception, L. conceptio, fr. concipere to conceive. See Conceive.]
1. The act of conceiving in the womb; the initiation of an embryonic animal life. I will greaty multiply thy sorrow and thy conception. Gen. iii. 16.
2. The state of being conceived; beginning. Joy had the like conception in our eyes. Shak.
3. The power or faculty of apprehending of forming an idea in the mind; the power of recalling a past sensation or perception. Under the article of conception, I shall confine myself to that faculty whose province it is to enable us to form a notion of our past sensations, or of the objects of sense that we have formerly perceived. Stewart.
4. The formation in the mind of an image, idea, or notion, apprehension. Conception consists in a conscious act of the understanding, bringing any given object or impression into the same class with any number of other objects or impression, by means of some character or characters common to them all. Coleridge.
4 more senses
5. The image, idea, or notion of any action or thing which is formed in the mind; a concept; a notion; a universal; the product of a rational belief or judgment. See Concept. He [Herodotus] says that the sun draws or attracts the water; a metaphorical term obviously intended to denote some more general and abstract conception than that of the visible operation which the word primarily signifies. Whewell.
6. Idea; purpose; design. Note this dangerous conception. Shak.
7. Conceit; affected sentiment or thought. [Obs.] He . . . is full of conceptions, points of epigram, and witticism. Dryden.
Syn. -- Idea; notion; perception; apprehemsion; comprehension.
Shades of meaning
Fernald has no entry of its own for conception; he lists it under fancy, idea.
Where he writes about it:
A conceit or fancy may be wholly unfounded, while a conception always has, or is believed to have, some answering reality. (Compare reason.) An intellectual fancy or conceit may be pleasing or amusing, but is never worth serious discussion; we speak of a mere fancy, a droll or odd conceit. — from fancy
The present popular use of idea makes it to signify any product of mental apprehension or activity, considered as an object of knowledge or thought; this coincides with the primitive sense at but a single point--that an idea is mental as opposed to anything substantial or physical; thus, almost any mental product, as a belief, conception, design, opinion, etc., may now be called an idea. — from idea