Learn Arabic (Modern Standard): يجري النهير الصغير قرب الجبل. - The small stream flows near the mountain.

The word النهير (an-nuhayr) is the diminutive form of نهر (nahr, meaning river). It follows the standard فُعَيْل (fu'ayl) pattern for three-letter roots. You take the root consonants n-h-r, put a dhamma on the first letter, a fatha on the second, and add a yaa before the last letter, giving you نُهَيْر.

Since النهير already means 'small river' or 'stream', isn't adding the adjective الصغير redundant?

In English, saying 'the small little river' might sound repetitive, but in Arabic, it is very common and natural to use an adjective like الصغير alongside a diminutive noun for emphasis. The diminutive النهير applies the grammatical pattern for smallness, while الصغير reinforces the physical size.

Why does قرب (near) end with a fatha in this sentence?

The word قرب (qurba) acts as an adverb of place (often called a spatial tharf). These words are typically in the accusative case (mansub), which is why it takes a fatha at the end. It forces the following noun, الجبل, into the genitive case (majrur) because they form an idaafa (possessive) construction.

I originally learned يجري as 'he runs'. Is it the standard verb for flowing water?

Yes! While you first learned يجري for physical running, it is the standard and most natural verb in Arabic to describe liquids flowing or streaming. You will frequently see it used for rivers, streams, and tears.