Concept, n.
Etymology: [L. conceptus (cf. neut. conceptum fetus), p. p. of concipere to conceive: cf. F. concept. See Conceit.]
An abstract general conception; a notion; a universal. The words conception, concept, notion, should be limited to the thought of what can not be represented in the imagination; as, the thought suggested by a general term. Sir W. Hamilton.
Shades of meaning
Fernald has no entry of its own for concept; he lists it under idea.
He lists it without comment; the entries above explain its neighbors.