Hypersonic

adjective; also noun (plural: hypersonics)

/ˌhaɪpəˈsɒnɪk/

Of, relating to, or denoting speeds equal to or exceeding Mach 5 (five times the speed of sound, approximately 6,125 km/h at sea level). Hypersonic flight presents extreme aerodynamic and thermal challenges. Two primary weapons categories are examined in UPSC context: Hypersonic Glide Vehicles (HGVs), which are boosted to high altitudes and then glide at hypersonic speeds along unpredictable trajectories evading conventional missile defences; and Hypersonic Cruise Missiles, powered throughout by scramjet engines. India conducted its first successful flight test of a Hypersonic Technology Demonstrator Vehicle (HSTDV) with a scramjet engine in September 2020 (DRDO); BrahMos-II (in development) will be a hypersonic cruise missile variant.

✍️ Usage in a UPSC answer

India's successful demonstration of scramjet-powered hypersonic flight through the HSTDV test of September 2020 positioned the country within a select technological club alongside the United States, Russia, and China, accelerating the strategic calculus of missile defence architecture in the Indo-Pacific.

Synonyms

ultra-high-speedMach 5+scramjet-speedbeyond supersonic

Antonyms

subsonicsupersonic (Mach 1–4)slow-flying

🌱 Word Family

hypersonic (adj/n), hypersonics (n, the field), supersonic (adj, Mach 1–5), Mach number (n), scramjet (n, the engine), glide vehicle (n)

🔡 Root

Greek hyper- = over, above, beyond; Latin sonicus = of sound (from sonus = sound) — 'beyond sonic speed'

📜 Etymology

Formed in the mid-20th century from the Greek prefix hyper- ('beyond') and sonic (from Latin sonus, 'sound'). The word was coined in aerodynamics in the 1940s; the Mach 5 threshold was defined by aerodynamicist H. Julian Allen at NACA. The distinction from supersonic (Mach 1–5) reflects qualitatively different aerodynamic and thermal phenomena at Mach 5+.

🧠 Memory Hook

HYPER (beyond) + SONIC (sound): faster than sound is supersonic (Mach 1+); BEYOND that into a qualitatively different regime (Mach 5+) is hypersonic. Hyper- always means extreme excess — hyperbole, hypermarket, hypertension. Mach 5 = 5× sound = hypersonic.

📝 Seen in UPSC Question Papers

Prelims 2022 — Defence Technology
Prelims 2022 — Defence Technology

Real UPSC previous-year questions whose text uses “Hypersonic” — proof this word earns its place on your list.

🔬 Science & Technology 📖 Seen in: Emerging Technologies — AI, Quantum Co...

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