There are several websites that offer a Spanish word of the day. If you subscribe to them you will receive in your email a new word everyday until you unsubscribe. Most of the sites provide a definition and some sentences to go along with the word.
There are 3 I recommend, if you sign up for all 3 then you can have 3 Spanish words of the day. They are:
Transparent Language Spanish Word of the Day
Spanish Pod 101 Word of the Day
For the Spanish phrase of the day go to 123 Teach Me.