English Parish Register freereg.rootsweb.com The Oxford Names Companion, OUP "Scottish Forenames" - Donald Whyte, FGH, FSG
Notes:
English and German feminine form of Philip, from Greek "horse lover".
Philippa appears in old documents in Latin, with appropriate case endings, as the normal feminine form of Philip. Less common spellings are Philipa, Phillipa and Phillippa.
Thanks to Donald Whyte who provided much of the initial information for this site.