Because proof is lacking, the dictionaries play safe by saying that the word “beggar” is probably just a derivative of beg, which in turn may have come from an unusual Old English term, bedecian.
But some scholars flout that theory; they believe that beggar was first in the language, with the verb, beg, derived from it, and that neither term was in use before the thirteenth century.
They explain the origin thus: About the year 1180, a priest of Liege, Lambert le Begue, founded a religious sisterhood, the members of which, from his name, were known as Beguines. They devoted themselves to a religious life and to chastity, but were permitted to leave the order for marriage.
At a subsequent date, probably in the early thirteenth century, a similar order for men became established. These members were called Beghards. But the organization of the brotherhood was very loosely drawn; it was possible for thieves and mendicants to go about the country, professing to be Beghards, and even before the end of the thirteenth century the order was held in low repute and its members persecuted.
But the name was already attached to such men, whether religious or not, who lived by asking for and receiving alms, to mendicants.
Thus, it is explained, the Beghards of the Low Countries became, by natural phonetic spelling, the beggars of England.