A system and method for identifying an unknown word's likely definition based upon a common social networking group is presented. A user receives a message and selects an unknown word in the message. In turn, the recipient client identifies a common social networking group between the sending client and the recipient client. The recipient client then uses the common social networking group to identify the unknown word's definitions using one or more unknown word repositories, such as the sending client unknown word repository, the recipient client unknown word repository, or a mutual client unknown word repository, which corresponds to a mutual client included in the common social networking group. Once the recipient client identifies the unknown word's definitions, the recipient client orders and displays the definitions based upon the common social networking group and social networking group frequency values.