5 syllables: I, co, sa, he, dral. Stress on he.
eye-koh-suh-HE-druhl
/aɪˌkoʊsəˈhedrəl/
Icosahedral is pronounced eye-koh-suh-HE-druhl (/aɪˌkoʊsəˈhedrəl/). It has five syllables (I-co-sa-he-dral), with the stress on "he". Icosahedral is a geometric adjective describing a shape whose surface is composed of twenty triangular faces, specifically relating to an icosahedron. It denotes symmetry and a high degree of regularity in three-dimensional form, often used in chemistry, virology, and mathematics to describe structures with twenty-faced geometry. The term emphasizes the polyhedron’s regularity and tessellation properties rather than mere coloration or size.
adjectiveIcosahedral is a geometric adjective describing a shape whose surface is composed of twenty triangular faces, specifically relating to an icosahedron. It denotes symmetry and a high degree of regularity in three-dimensional form, often used in chemistry, virology, and mathematics to describe structures with twenty-faced geometry. The term emphasizes the polyhedron’s regularity and tessellation properties rather than mere coloration or size.
"The virus exhibits an icosahedral capsid, giving it a highly stable, symmetric shell."
"Researchers modeled the protein complex as an icosahedral structure to understand its assembly."
"The crystallographer noted an icosahedral arrangement of subunits within the particle."
Pronounce as ɪˌkɒsəˈhedrəl in UK or ɪˌkoʊsəˈhiːdrəl in US, with primary stress on the fourth syllable -hedr- and secondary on -i- or -ko-. Break it into i-co-sah-hed-ral, with a clear 'hed' as in helmet and a soft 'r' before the final 'əl'. Audio reference: consult standard dictionaries or Pronounce resources for guided pronunciation.
Common errors include stressing the wrong syllable (placing primary stress on i- or co- rather than -hed-), mispronouncing the 'icosa' sequence as 'eye-co-say-uh' instead of 'ee-ko-suh-', and softening the final -ral too much into a silent or schwa-like ending. Correct by practicing the 'hed' cluster with a crisp 'd' and keeping the final -ral as 'ruh-l' rather than an abrupt stop.
In US English, you’ll typically hear ɪˌkoʊˈsæˌhedrəl or ɪˌkoʊˌsəˈhiːdrəl with +pronounced long e in -hi-, while UK English often features ɪˌkɒsəˈhedrəl with a shorter first vowel and less rhoticity in some speakers. Australian tends toward ɪˈkɒsə hèdrəl with a strong vowel in the first two syllables and a lightly rolled or tapped r depending on speaker. The primary stress remains on the -hedr- syllable across variants.
The difficulty lies in the multi-syllabic length and the cluster -sa-hedr- with the dense consonant sequence around -hedr-. The medial syllables contain vowel transitions (i- to -co- to -sa-) that require precise tongue positioning and a clear 'd' before the final -ral. Additionally, the exact rhythm of the three main stresses and the non-reduced vowels in the middle can be challenging for non-technical speakers.
There are no silent letters in Icosahedral; every letter participates in pronunciation. The challenge is more about the length and the sequence of consonant and vowel sounds in the middle of the word, not about silent segments. Correct by segmenting into five phonetic units and articulating each clearly: i-/ɪ/; ko-/koʊ/ or kɒ/ depending on accent; sa-/sə/; he-/hed/; dral-/drəl.
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US: typically ɪˌkoʊsəˈhiːdrəl; pronounce the mid vowels clearly, stress the -hedr- syllable, and keep the final -əl light. UK: often ɪˌkɒsəˈhedrə l; shorter first vowel, strong -hedr-; non-rhotic or lightly rhotic depending on speaker. AU: ɪˈkɒsəhedrəl; stronger final syllable clarity, vowel quality closer to AU standard; keep the -dr- cluster crisp.
The word icosahedral comes from the Greek icosa- meaning twenty (from eikosi, ‘twenty’) and -hedral from the Greek hedra, meaning a face or base of a polyhedron. Its first known use in scientific literature appears in the 19th or early 20th century as polyhedral geometry and crystallography advanced in tandem; mathematicians and chemists adopted icosahedral and related terms to precisely describe the symmetry of certain molecules and viruses. The combination of icosa- with -hedral captures the idea of a twenty-faced polyhedron with a well-defined set of triangular faces. Over time, the term has become common in virology (capsid symmetry), crystallography (unit cells and face arrangements), and materials science (nano-structures) due to its concise descriptive power for highly regular, symmetric shapes. The word sits at the intersection of geometry and molecular science, reflecting a robust, universal schema for describing shapes that are impossible to tile with fewer than twenty triangular faces without sacrificing regularity.
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Words that rhyme with "Icosahedral"
-ral sounds
Practice with these rhyming pairs to improve your pronunciation consistency:
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