Yours, Etc.: Origins and Uses of 8 Sign-Offs
early 15c., "dull, blunted," from Middle French obtus (fem. obtuse), from Latin obtusus "blunted, dull," also used figuratively, past participle of obtundere "to beat against, make dull," from ob "against" (see ob-) + tundere "to beat," from PIE *(s)tud-e- "to beat, strike, push, thrust," from root *(s)teu- "to push, stick, knock, beat" (cf. Latin tudes "hammer," Sanskrit tudati "he thrusts"). Sense of "stupid" is first found c.1500. Related: Obtusely; obtuseness.
obtuse ob·tuse (ŏb-tōōs', -tyōōs', əb-)
Lacking quickness of perception or intellect.
Not sharp or acute; blunt.