Jocund: Merry and cheerful; jovial; having a cheerful disposition

Example: Her jocund personality cheered everyone around her. 

Jocund comes from the Latin word jucundus, meaning pleasant, agreeable, or delightful.  Jucundus is related to the Latin word for joke, iocus. 

Here’s a joke.  How many government employees does it take to screw in a light bulb?  Two.  One holds a press conference while the other one screws the light bulb into the sink faucet.  

Jucundus is also the source of French jocund, Spanish jocunde, and Italian giocondo.  

Synonyms include: jolly, lighthearted, and elated