Synonyms for the word "boastive" can include arrogant, conceited, proud, vainglorious, vaunting, self-important, overbearing, egotistical, pompous, pretentious, and braggadocious. Each of these words conveys a sense of excessive self-pride or the tendency to boast or inflate one's own abilities or achievements. While these words emphasize different nuances of boastiveness, they all refer to individuals who exhibit an inflated sense of self-importance or a tendency to excessively brag about themselves. So, whether it's an arrogant co-worker, a conceited celebrity, or a pretentious neighbor, there are numerous synonyms to describe individuals who cannot resist boasting about their accomplishments.