Translation guide
The English word 'thousands' refers to a large number, specifically multiples of 1,000. In Japanese, expressing this concept depends on whether you are counting exact thousands, describing an approximate large quantity, or using it in idiomatic expressions.
To state a specific number in the thousands.
Use the number followed by 千 (せん) for exact thousands. For numbers like 3,000, say 三千 (さんぜん). Note the sound changes for certain numbers: 1,000 is 千 (せん), 3,000 is 三千 (さんぜん), 8,000 is 八千 (はっせん).
この車は二千ドルです。
This car is two thousand dollars.
五千人がイベントに参加した。
Five thousand people participated in the event.
To express an indefinite large quantity, like 'thousands of people'.
数千 (すうせん) means 'several thousand' or 'thousands of'. It is the most common way to express an approximate number in the thousands.
数千人の観客が集まった。
Thousands of spectators gathered.
数千匹の魚が泳いでいる。
Thousands of fish are swimming.
何千 (なんぜん) means 'many thousands', emphasizing a large, indefinite number. The も adds emphasis.
何千もの星が輝いている。
Thousands of stars are shining.
幾千 (いくせん) is a more literary or formal way to say 'thousands of'. It is less common in everyday speech.
幾千もの兵士が戦場に散った。
Thousands of soldiers fell on the battlefield.
To express a very large, often uncountable number, similar to 'thousands and thousands'.
This phrase literally means 'thousands and tens of thousands', used to emphasize an enormous number.
何千何万という人々がそのコンサートに来た。
Thousands upon thousands of people came to the concert.
無数 (むすう) means 'countless' or 'innumerable'. It is not specific to thousands but conveys a very large number.
無数の星が空に見える。
Countless stars are visible in the sky.
English uses 'thousands' as a noun (e.g., 'thousands of...'), but Japanese typically uses a number + counter or a phrase like 数千. Do not try to translate 'thousands' in isolation without a counter or noun.
数千人が来た。
Thousands of people came.
数千 (すうせん) is neutral and simply means 'several thousand'. 何千 (なんぜん) is more emphatic, like 'many thousands' or 'thousands and thousands'. Use 数千 for most situations.
毎年数千人の人々がこの寺を訪れる。
Thousands of people visit this temple every year.
その会社は数千ドルを失った。
The company lost thousands of dollars.