Adjective
preposterous - Contrary to reason or common sense; utterly absurd or ridiculous.
When Sandy's stock broker called and suggested that he sell half his stocks because he felt the market was overvalued, Sandy thought the idea was preposterous - but it turned out that his stock broker was right.
scintillating - Describing someone or something that is exceptionally witty and entertaining, and is intellectually or emotinally stimulating.
Her scintillating conversation captivated those she talked to at the dinner party, leaving them laughing and enjoying themseles.