conceit

Short definition from Wiktionary

Noun

1. 1
   Something conceived in the mind; an idea, a thought.
2. 2
   The faculty of conceiving ideas; mental faculty; apprehension.
3. 3
   Quickness of apprehension; active imagination; lively fancy.
4. 4
   Opinion, (neutral) judgment.
5. 5
   Esteem, favourable opinion.
6. 6
   A novel or fanciful idea; a whim.
7. 7
   An ingenious expression or metaphorical idea, especially in extended form or used as a literary or rhetorical device.
8. 8
   Overly high self-esteem; vain pride; hubris.
9. 9
   Design; pattern.

Verb

1. 1
   To form an idea; to think.
2. 2
   To conceive.