A sop is a piece of bread or toast that is drenched in liquid and then eaten. In medieval cuisine, sops were very common; they were served with broth, soup or wine, and then picked apart into smaller pieces to soak in the liquid. At elaborate feasts, bread was often pre-cut into finger-sized pieces rather than broken off by the diners themselves. French onion soup, which took its current form in the 18th century, can be considered a modern-day sop.
The word "soup" is a cognate of "sop", both stemming ultimately from the same Germanic source. The word is mentioned prominently in the Bible, King James Version:
When Jesus had thus said, he was troubled in spirit, and testified, and said, Verily, verily, I say unto you, that one of you shall betray me. Then the disciples looked one on another, doubting of whom he spake. Now there was leaning on Jesus' bosom one of his disciples, whom Jesus loved. Simon Peter therefore beckoned to him, that he should ask who it should be of whom he spake. He then lying on Jesus' breast saith unto him, Lord, who is it? Jesus answered, He it is, to whom I shall give a sop, when I have dipped it. And when he had dipped the sop, he gave it to Judas Iscariot, the son of Simon. ( John 13:21-26 )
In 19th century Australia, Sop referred to a dish consisting of stale damper, soaked in cold tea and served with a dollop of jam on top for taste. This was mainly used in prisons and poor-houses, as well as institution such as asylums. Sop coloquially stood for S***-On-Plate and was not a desirable dish to be served.
The expression "milksop" describes a person as weak and indecisive. Its connotation is similar to that of "milquetoast".
The term "supper" derives from "SOP", and the expression "toast of the town" derives from the practices of dipping spiced toasted bread into liquid, and of honoring a dinner guest by referring to him or her by that term, which implies he or she adds spice to the dinner party.