The term 'BIG HEAD' is a phrase used to describe someone who has an inflated sense of self-importance. This can be seen in the crossword solutions, such as EGO (3 letters), ALE (3 letters), EGOIST (6 letters), MEGA (4 letters), EGOCENTRICITY (13 letters), BOASTFUL (8 letters), and BRAGGING (8 letters). All of these words refer to someone who is excessively proud of themselves and their accomplishments, which is the definition of having a 'BIG HEAD'.