What does Jormungandr mean?
Old Norse Jormungandr, the Midgard/World Serpent that encircles the earth. From jormun- 'huge, vast' + gandr, an ambiguous word covering 'serpent/staff/magical being', commonly read 'giant serpent'. Flag: a mythological serpent's NAME, and the second element is genuinely ambiguous (also 'giant staff/binding'), so the 'serpent' reading is the usual but not the only one.
What does Ulf mean?
From the Old Norse 'ulfr', meaning 'wolf'. A common standalone name in medieval Scandinavia and the source of the '-ulf' ending in many Norse compound names.