masc. proper name, from Old North French Willaume, Norman form of French Guillaume, of Germanic origin (cognates: Old High German Willahelm, German Wilhelm), from willio "will" (see will (n.)) + helma "helmet," from Proto-Germanic *helmaz "protective covering" (from PIE root *kel- (1) "to cover, conceal, save;" compare helm (n.2)). After the Conquest, the most popular given name in England until supplanted by John.
fem. proper name, name of the faithful wife in the "Odyssey," from Greek Pēnelopē, Pēnelopeia, which is perhaps related to pēne "thread on the bobbin," from pēnos "web," cognate with Latin pannus "cloth garment" (see pane (n.)). But Beekes suggests rather a connection with pēnelops "duck or wild goose with colored neck." Used in English as the type of the virtuous wife (1580) as it was in Latin.
Penelope, the daughter of Icarus, was a rare and perfect example of chastity. For though it was generally thought that her husband Ulysses was dead, since he had been absent from her twenty years; yet, neither the desires of her parents, nor the solicitations of her lovers, could prevail on her to marry another man, and to violate the promises of constancy which she gave to her husband when he departed. And when many noblemen courted her, and even threatened her with ruin, unless she declared which of them should marry her, she desired that the choice might be deferred till she had finished the piece of needle-work about which she was then employed: but undoing by night what she had worked by day, she delayed them till Ulysses returned and killed them all. Hence came the proverb, "To weave Penelope's web;" that is, to labour in vain; when one hand destroys what the other has wrought. [Andrew Tooke, "The Pantheon, Representing the Fabulous Histories of the Heathen Gods and Most Illustrious Heroes, in a Plain and Familiar Method," London: 1824]