Origin: bef. 900; ME
beggen, by assimilation from OE
*bedican, syncopated var. of
bedecian to beg; cf. Goth
bidagwa beggar.
See bead 
Synonyms:
2. entreat, pray, beseech, petition. Beg and request are used in certain conventional formulas, in the sense of ask. Beg, once a part of many formal expressions used in letter writing, debate, etc., is now used chiefly in such courteous formulas as I beg your pardon; The Committee begs to report, etc. Request, more impersonal and now more formal, is used in giving courteous orders (You are requested to report) and in commercial formulas like to request payment.