What it means

یک‌سوم (yek-sevvom) is the standard Persian expression for “one third,” meaning one part out of three equal parts. It is a purely native Persian compound formed from یک (yek, “one”) and سوم (sevvom, the ordinal of سه, “three”). The word follows the same pattern as other Persian fractions, making it easy to recognise once you know the ordinal numbers. In everyday speech you will hear it in the context of cooking, sharing, construction measurements, and school mathematics.

How to use it

• یک‌سوم شیر رو اضافه کن. (Yek-sevvom-e shir ro ezâfe kon.) “Add one third of the milk.”
• یک‌سوم درآمدمو پس‌انداز می‌کنم. (Yek-sevvom-e darâmad-amo pas-andâz mikonam.) “I save one third of my income.”
• این کار یک‌سوم زمان کمتری می‌بره. (In kâr yek-sevvom zamân-e kamtari mibare.) “This task takes one third less time.”
• یک‌سوم نمرات قبولی بود. (Yek-sevvom-e namarât qabuli bud.) “One third of the grades were passing.”

Cultural note

In Iranian cooking traditions, dividing dough, rice, or stews into thirds is a common technique, and یک‌سوم appears frequently in traditional recipes. Persian fractions built with ordinal suffixes are fully productive, meaning speakers can form any unit fraction on the spot without needing a special word for it, which is one reason Persian math vocabulary feels systematic and learnable even at early levels.

References

• Dehkhoda
• Vajehyab

What it means

یک سوم (yek-sevvom) is one third, the fraction 1/3. The structure is transparent: یک (one) plus سوم (sevvom, third), the ordinal form of سه (se, three). Persian builds most of its fractions this way. یک پنجم (yek-panjom) is one fifth, یک ششم (yek-sheshom) is one sixth, یک دهم (yek-dahom) is one tenth. The pattern is reliable: یک plus the ordinal of the denominator gives you the fraction.

Where you will meet it

yek-sevvom shows up in measurement, statistics, news reporting, and academic writing. You hear it on the news (یک سوم جمعیت, yek-sevvom-e jamiyat, one third of the population), in a recipe (یک سوم پیمانه, yek-sevvom-e peymane, one third of a cup), in business reports (سهم ما یک سوم است, sahm-e ma yek-sevvom ast, our share is one third). Casual conversation tends to round down to half or up to half, so fractions like a third sit naturally in more measured contexts. When you do need to say a third precisely, this is the word.

Among the three core fractions on the site, this one is the most academic feeling. Nim is everywhere, yek-charak holds time and old weights, yek-sevvom does the work of precise modern measurement.

How to use it

yek-sevvom-e mardom be tehran zendegi mikonand.

One third of the people live in Tehran.

یک سوم مردم در تهران زندگی می‌کنند.

yek-sevvom peymane shekar lazem darim.

We need one third of a cup of sugar.

یک سوم پیمانه شکر لازم داریم.

faqat yek-sevvom-e kar tamum shode.

Only one third of the work is done.

فقط یک سوم کار تمام شده.

Where it comes from

The pieces are both ancient native Persian: یک (yek, one) and سوم (sevvom), the ordinal of سه (se, three). The ordinal suffix -om is the standard Persian form, the same one that builds دوم (dovvom, second), چهارم (chaharom, fourth), پنجم (panjom, fifth), and so on. The fraction formula yek plus ordinal is a clean grammatical construction, transparent to any Persian speaker, and it scales to any denominator without strain.

In our voice

Learn the formula and you have unlocked every Persian fraction except half and quarter. Once یک plus ordinal is in your ear, you can build a fifth, an eighth, a hundredth on the fly. Yek-sevvom is your training wheel for the whole system.

References

• Dehkhoda, سوم
• Vajehyab, یک سوم