Gulielmus

Latin

Alternative forms

• Wilielmus, Guilhelmus, Guilielmus, Guillermus, Vilhelmus, Wilhelmus, Willelmus

Etymology

Etymology tree

Proto-Indo-European *welh₁-der.

Proto-Germanic *wiljaną

Proto-Germanic *wiljô

Proto-Indo-European *ḱel-der.

Proto-Indo-European *ḱelmos?

Proto-Germanic *helmaz

Proto-Germanic *Wiljahelmaz

Proto-West Germanic *Willjahelmbor.

Romancebor.

Latin Gulielmus

Borrowed from a Romance language, borrowed from Proto-West Germanic *Willjahelm, from Proto-Germanic *Wiljahelmaz (literally “Will-Helmet”), mainly via Old French Willame. First attested as Willelmus in AD 804.

Pronunciation

• (modern Italianate Ecclesiastical) IPA^(key): [ɡu.liˈɛl.mus]

Proper noun

Gulielmus m (genitive Gulielmī); second declension

1. (Medieval Latin) a male given name, equivalent to English William [9th c.]

Declension

Second-declension noun.

	singular	plural
nominative	Gulielmus	Gulielmī
genitive	Gulielmī	Gulielmōrum
dative	Gulielmō	Gulielmīs
accusative	Gulielmum	Gulielmōs
ablative	Gulielmō	Gulielmīs
vocative	Gulielme	Gulielmī

Descendants

• → Albanian: Golem, Gulam, Gjyiam
• → Greek: Γουλιέλμος (Gouliélmos)

Descendants listed below are only partly taken or influenced by the Latin term but primarily borrowed from another source, such as the Old French or directly from Germanic.

• → Catalan: Guillem (semi-learned)
• → Galician: Guillerme (semi-learned)
• → Italian: Guglielmo (semi-learned)
• → Occitan: Guilhèm (semi-learned)
• →? Old English: Willelm
• (Old French: Willame (see there for further descendants))
• → Portuguese: Guilherme (semi-learned)
• → Spanish: Guillermo (semi-learned)

References

• James Fred Patin, Jr. (2026), “Guillaume, Comte de Toulouse, Marquis de Septimania.”, in Geni.com‎^[1]