obtuse (English)

Where does "obtuse" come from?

The English adjective 'obtuse' descends from Middle English 'obtuse', which came from the Latin 'obtūsus', meaning 'blunt, dull; obtuse'[1]. The Latin form serves as the past participle of 'obtundere', meaning 'to batter, beat, strike; to blunt, dull'[1]. This Latin verb combines 'ob-', meaning 'against', and 'tundō', meaning 'to beat, strike; to bruise, crush, pound'[1]. The root 'tundō' traces further back to the Proto-Indo-European root '*(s)tewd-', meaning 'to hit' or 'to push'[1][3].

Open questions

The ultimate Proto-Indo-European root is reconstructed as '*(s)tewd-', which is extended from '*(s)tew-'. [1] [3]

Full etymology tree

obtuse (English), 'Blunt; not sharp, pointed, or acute in form.'
- inherited obtuse (Middle English)
  - borrowed obtusus (Latin), 'struck, beaten, buffeted'
    - derived obtundere (Latin), 'second-person singular future passive indicative of obtundō'
      - derived obtundo (Latin), 'to strike, beat or batter'
        compound ob- (Latin), 'towards; against'
        compound tundo (Latin), 'to beat, strike, buffet'
        inherited *tundō (Proto-Italic), 'to beat, strike'
        inherited *(s)tunédti (Proto-Indo-European), 'to be pushing, hitting'
        derived *(s)tewd- (Proto-Indo-European), 'to push, to hit'
        derived *(s)tew- (Proto-Indo-European), 'to push, to hit'

Ancestors

*(s)tewd- (Proto-Indo-European)
obtusus (Latin)

Descendants and derived words

nonobtuse (English)
obtuse angle (English)
obtuse-angled (English)
obtuse-angled triangle (English)
obtuse-angular (English)
obtuse horn shell (English)
obtusely (English)
obtuseness (English)
obtuse triangle (English)
obtusish (English)
obtusity (English)
subobtuse (English)

Sources

Updated August 2026

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Etymology data from Wiktionary, CC BY-SA 4.0 · About Miraris