Here for your viewing pleasure is Claude Monet's Impression - Sunrise (1872), the painting that gave the name to the movement.
Painted of the sea outside his Le Havre window after lengthy study, and pressed for a name, Monet said he could hardly just call it 'Le Havre.' So Impressions - Sunrise it was. Said critic Jules-Antoine Castagnary,
If one wishes to characterise and explain the [new artists] with a single word, then one would have to coin the word impressionists. They are impressionists in that they do not render a landscape, but the sensation produced by the landscape. The word itself has passed into their language: in the catalogue the Sunrise by Monet is called not landscape, but impression.You can see how he used colour to produce his impression briefly explained here.
And as always, click to enlarge. (You know you want to.)