bridegroom: the man who is being married, the groom at a wedding
In everyday Greek this is simply the word for the groom, the man at the center of a wedding beside his bride (νύμφη). The New Testament uses it that plain way only twice: the master of the feast speaks to the actual groom at the wedding in Cana, and a doomed Babylon is pictured with the voices of ordinary married life falling silent.
Everywhere else the word points past the wedding to Jesus. When people ask why his followers do not fast, he answers that guests cannot mourn while the bridegroom is still with them, and warns that the day is coming when he will be taken away from them. John the Baptist calls himself only the bridegroom's friend, glad to step aside for the one to whom the bride belongs. In the story of the ten young women, everything turns on being ready when the bridegroom finally arrives.
This is more than a passing comparison. The Old Testament again and again pictures God as the husband of his people, so calling Jesus the bridegroom quietly sets him where God stood in that older picture. The image says both that his coming is a wedding, a thing to celebrate, and that his people are the ones he has bound himself to. The Hebrew word for a bridegroom (חָתָן) shares the same wedding setting, though without that developed theme.