k/k/
Raise the back of your tongue to touch the soft palate (velum). Stop the air, then release.
How to pronounce costumes in American English
KAH·stoomz
Start here
Americans pronounce costumes as KAH-stoomz (/ˈkɑstumz/). Stress falls on the first syllable — keep everything else short and quick. You'll hear it in sentences like "She loves cosplaying and making her own costumes for conventions".
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Sound by sound
Every sound in "costumes".
2 syllables, 7 sounds. Tap a syllable to jump to its row, then explore each sound's mouth shape and how it's made.
ah/ɑ/
Relax your lips and drop your jaw significantly. The tongue tip lightly touches behind the bottom front teeth and the back part of the tongue presses down a little to create more dark space in the back of the mouth.
s/s/
Place your tongue tip near the roof of your mouth behind your top teeth. Push air through the narrow gap. No voicing.
t/t/
Touch the tip or front edge of your tongue to the roof of your mouth just behind your teeth. Keep your jaw relaxed. Stop the air, then release with a puff.
oo/u/
Round your lips into a tight circle. Let your tongue rest in the middle of your mouth, slightly raised.
m/m/
Press your lips together. Air flows through your nose. Vocal cords vibrate.
z/z/
Same position as S, but add vocal cord vibration. Feel the buzz.
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Watch out
Common pronunciation mistakes in American English.
The textbook way isn't wrong — it's just not how anyone actually says it.
01
Stressing the wrong syllable.
Stress falls on the first syllable, not the others. Stretch KAH — keep everything else short and quick.
kah·STOOMZ→KAH·stoomz
Questions
Questions people ask about this.
How is "costumes" stressed in American English?
Stress falls on the first syllable — say "KAH" with a longer, fuller vowel and keep every other syllable short and quick. The respell "KAH-stoomz" marks the stressed syllable in capitals so the rhythm is easy to read at a glance.
Is the American pronunciation of "costumes" different from British English?
American English uses different vowel shapes, a relaxed retroflex R, and connected-speech tricks like flap-T and glottal-stop T that British Received Pronunciation generally avoids. The respell "KAH-stoomz" reflects the casual American form; British dictionaries typically print a citation form with crisper consonants and different vowel choices.
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