2 syllables: air, foil. Stress on air.
ER-foyl
/ˈɛˌɹfɔɪl/
airfoil is pronounced ER-foyl (/ˈɛˌɹfɔɪl/). It has two syllables (air-foil), with the stress on "air". Airfoil refers to a streamlined surface or blade designed to generate lift in an aerodynamic flow, such as on wings, propellers, or turbines. The term combines air with foil, indicating a thin, curved shape optimized to manage air movement. In practice, airfoils influence lift, drag, and overall efficiency in engineering contexts and aerodynamic design.
Airfoil refers to a streamlined surface or blade designed to generate lift in an aerodynamic flow, such as on wings, propellers, or turbines. The term combines air with foil, indicating a thin, curved shape optimized to manage air movement. In practice, airfoils influence lift, drag, and overall efficiency in engineering contexts and aerodynamic design.
"The aircraft wing is an airfoil that creates lift as air moves over and under its surface."
"Engineers tested a new airfoil profile to reduce drag at high speeds."
"The wind turbine blade acts as an airfoil to convert wind energy into rotational motion."
Airfoil is pronounced as /ˈɛərˌfɔɪl/ in US English and /ˈeəˌfɔɪl/ in UK/AU. The stress pattern is first-syllable primary stress on “air” and secondary stress on the second syllable “foil.” Start with a clear “air” diphthong, then glide into “foil” with /ɔɪ/ as in “boy” but linked to the preceding vowel. Keep the tongue high on /ɔɪ/ and ensure the /r/ is either rhotacized in US (ˈɛər) or non-rhotacized in non-rhotic varieties. Listening to the sequence helps: air + foil, smoothly connected. IPA reference: US /ˈɛərˌfɔɪl/, UK/AU /ˈeəˌfɔɪl/.
Common errors include misplacing the /r/ in non-rhotic accents or splitting the diphthong /ɛər/ into separate sounds. To correct: ensure the /ˈɛər/ (US) or /ˈeə/ (UK/AU) is a fused, rising diphthong rather than two discrete vowels, and connect the /fɔɪl/ with the first syllable without a hard pause. Another mistake is pronouncing /ɔɪ/ as a short /ɒɪ/ or flattening the glide into /aɪ/. Practice with lip rounding and a smooth transition antara /ɛər/ and /fɔɪl/.
In US English, /ˈɛərˌfɔɪl/ features a rhotic /r/ and a clear /ɛər/ onset. UK/AU typically use /ˈeəˌfɔɪl/, with non-rhotic speech where /r/ is not pronounced at the end of syllables. The /ɔɪ/ diphthong remains, but vowel quality can sound closer to /ɔɪ/ with slightly rounded lips in Australian speech. The main differences are rhoticity and the initial vowel quality, while the second syllable maintains /fɔɪl/ across accents. Audio references can reinforce the subtle shifts in onset and linking.
It challenges learners with a prominent diphthong in the first syllable and a smooth /ɔɪ/ glide into the second syllable, plus potential rhotic subtlety in American speech. The /ˈɛər/ or /ˈeə/ onset demands precise tongue position and lip rounding, while the /fɔɪl/ requires a controlled lip closure and gradual release into the glide. Mastery comes from practicing the sequence slowly, then increasing speed while keeping the two syllables distinctly linked and stress-balanced.
A distinctive feature is the strong liaison between the first syllable and the diphthong in the second, producing /ˈɛərˌfɔɪl/ or /ˈeəˌfɔɪl/ with minimal intrasegment pauses. You’ll often hear a very slight linking that makes the word feel like a compound of air + foil. Its pronunciation hinges on maintaining the clear /f/ onset for the second syllable while preserving the air-like initial vowel, without truncating either part.
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The word airfoil comes from air + foil. Foil in this sense derives from the Old French fel, later French foil meaning a leaf or blade, with broader meanings extending to a sword blade or a foil used in fencing. In aviation and engineering, airfoil has been used since the early 20th century to denote the cross-sectional shape of a wing or blade that interacts with air to produce lift. The first known uses trace to early aerodynamic texts as scientists and engineers sought a precise term to describe the curved, streamlined section of wings and propellers. The compound indicates a thin, curved profile (“foil”) designed to manage airflow (“air”). Over time, airfoil has become a standard technical term in aerospace, mechanical, and energy industries, remaining consistent in English usage while sometimes appearing in higher education and professional literature to specify cross-sectional geometry of lifting surfaces. The shift from general “foil” to the engineering sense emphasizes a shape optimized for minimizing pressure drag and maximizing lift-to-drag ratio under various Reynolds numbers and flow regimes.
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💡 These words have similar meanings to "airfoil" and can often be used interchangeably.
🔄 These words have opposite meanings to "airfoil" and show contrast in usage.
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Words that rhyme with "airfoil"
-oil sounds
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