anticlimax

noun

1. an event, conclusion, statement, etc., that is far less important, powerful, or striking than expected.
2. a descent in power, quality, dignity, etc.; a disappointing, weak, or inglorious conclusion: After serving as president, he may find life in retirement an anticlimax.
3. a noticeable or ludicrous descent from lofty ideas or expressions to banalities or commonplace remarks: We were amused by the anticlimax of the company’s motto: “For God, for country, and for Acme Gasworks.”

noun

1. a disappointing or ineffective conclusion to a series of events, etc
2. a sudden change from a serious subject to one that is disappointing or ludicrous
3. rhetoric a descent in discourse from the significant or important to the trivial, inconsequential, etc