Peggy f
English: variant of MAGGIE (SEE Maggie), or of the obsolete Meggie, both pet forms of MARGARET (SEE Margaret). The reason for the alternation of M- and P-, which occurs also in Molly/Polly, is not known; it has been ascribed to Celtic influence, but this particular alternation does not correspond to any of the usual mutational patterns in Celtic languages.
Short form: Peg.
First names dictionary. 2012.