sore, ulcer, wound
From earlier *olcos, from Proto-Italic *elkos, from Proto-Indo-European *h₁élḱos (“wound, illness, ulcer”), from the root *h₁elḱ-; compare Ancient Greek ἕλκος (hélkos, “wound, ulcer”), English ill. Sanskrit अर्शस् (árśas, “hemorrhoids”).
Practice speaking and memorizing "ulcus" and many other words and sentences in Latin.