The word 'ulcer' entered English in the late 14th century from the Old French 'ulcere', which itself derived from the Latin 'ulcus' (genitive: 'ulceris'), meaning 'a sore, wound, or ulcer'. The Latin term can be traced back to the Proto-Indo-European root elk-es-, which meant 'wound' and is also the source of the Greek 'helkos'. The semantic journey is remarkably direct: from an ancient Indo-European concept for a wound, to a specific medical term in Latin, and into English with its core meaning intact, later extended metaphorically to describe a corrosive or festering problem in a system.

The modern English word 'ulcer' is a simplex loanword from Latin. It is not productively segmented into smaller meaningful parts within its current English spelling.