foolishly emotional and tearful, overly sentimental
—When some people drink too much, they can’t stop laughing. Bill, on the other hand, is a maudlin drunk. He cries over every little thing. 

The Gospel-writer Luke tells the story of a woman who shows her devotion to Jesus by “anointing” his feet:

Then when a woman of that town, who was a sinner, learned that Jesus was dining at the Pharisee’s house, she brought an alabaster jar of perfumed oil. As she stood behind him at his feet, weeping, she began to wet his feet with her tears. She wiped them with her hair, kissed them, and anointed them with the perfumed oil. (Luke 7:37, 38)

Though the woman is not named, some believe this woman to be Mary Magdalene. This Mary is mentioned by Luke in the next chapter as one of the women who traveled with Jesus, along with his 12 closest disciples:

Some time afterward he went on through towns and villages, preaching and proclaiming the good news of the kingdom of God. The twelve were with him, and also some women who had been healed of evil spirits and disabilities: Mary (called Magdalene), from whom seven demons had gone out, and Joanna the wife of Cuza (Herod’s household manager), Susanna, and many others who provided for them out of their own resources. (Luke 8:1-3)

Mary was called Magdalene because she came from the town of Magdala. The Middle English form of Magdeline is Maudelen, which gives us maudlin.

Because the woman washed Jesus’ feet with her tears, maudlin now refers to someone who is weepy. And even though Mary Magdalene represents sincere sorrow and repentance, today’s maudlin is used to refer to someone who is overly tearful or to something, such as a story, that is sentimental in a foolish way.