I just finished reading a post at La Ortografía Infinita and found a new word to add to my Spanish vocabulary. The title of the post is 15 palabras del español que escriben mal hasta los más inteligentes. It lists the 15 words that even the smartest people spell incorrectly and offers a quiz so that you can test your own spelling. A new Spanish word that I learned from the test is nocivo.
Nocivo means harmful, injurious, damaging. Here is an example sentence: El tabaco es nocivo por el alquitrán y la nicotina que contiene. (Tobacco is harmful due to the tar and nicotine that it contains.)
You can take the test to see if you can spell the 15 Spanish words that many people often misspell at La Ortografía Infinita.