verb
solemnize
SOL-um-nyze/ˈsɑːləmnaɪz/
To perform a formal ceremony, especially a marriage.
A judge solemnizes the marriage in a brief courthouse ceremony.

Etymology
The ceremonial base becomes an action through the verb-forming ending: to honor or celebrate with ceremonies. Solemnizing a marriage preserves that ceremonial meaning rather than simply meaning to make something serious.
In context
will you solemnize our blessed Union not unless you truly love each other
More examples
- The couple asks their minister to solemnize their marriage.
- State law determines who may solemnize a marriage.
- Their marriage was solemnized in a small chapel.
Forms
solemnize · solemnizes · solemnized · solemnizing
solemnization noun — The formal performance of a ceremony.