Japanese Morphology: -sen

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Just to complete the set in elementary Japanese, let’s talk about “sen,” which is the number turned suffix for 1000.

For this set, in order to create a rule that’s even worth mentioning, I will be using a version of 1000 pronounced “issen,” which is used when counting really big numbers in big denominations. However, if one just wants to say 1000, my understanding is that “sen” in its standalone form (like hyaku) is the only acceptable way of saying it.

Let’s look at the set:

1000 Issen
2000 Nisen
3000 Sanzen
4000 Yonsen
5000 Gosen
6000 Rokusen
7000 Nanasen
8000 Hassen
9000 Kyuusen

Here we have 3 variations of the one suffix “sen.”

“ssen” (1, 8)
“zen” (3)
“sen” (2, 4, 5, 6, 7, 9)

This is really easy. So let’s just have at it.

The Thousand Rule

Let’s get our main lexemes lined up (as always)


1) If the main lexeme ends in /chi/, then drop /chi/ and add the “sssen” variation.

Ichi (ends in /chi/; /chi/ drops) —> Issen (DONE)
Hachi (ends in /chi/; /chi/ drops) —> Hassen (DONE)

2) If the main lexeme ends in an unrounded vowel + a nasal, then it takes the “zen” variation.

Issen (DONE) [Step 1]
Ni  (does not end in a nasal, n/a, ×)
San (ends in an unrounded vowel + a nasal) —> Sanzen (DONE)
Yon (does not end in a unrounded vowel + a nasal, n/a, ×)
Go (does not end in a nasal, n/a, ×)
Roku (does not end in a nasal, n/a, ×)
Nana (does not end in a nasal, n/a, ×)
Hassen (DONE) [Step 1]
Kyuu (does not end in a nasal, n/a, ×)

3) Everything else takes the “sen” variation.

Issen (DONE) [Step 1]
Ni —> Nisen (DONE)
Sanzen (DONE) [Step 2]
Yon —> Yonsen (DONE)
Go —> Gosen (DONE)
Roku —> Rokusen (DONE)
Nana —> Nanasen (DONE)
Hassen (DONE) [Step 1]
Kyuu —> Kyuusen (DONE)

Without “Issen,” I have only two very different exceptions to an otherwise very regular “sen” rule. With “Issen,” I can at least give a reason for “Hassen” to be the way it is. In the case of “sanzen,” you see a similar case of voicing as with “sanbyaku” and with “yon” remaining one of the numbers to change in the 3rd step. I suspect that counters have a small number of patterns that they follow. The three patterns I showed today may correspond to some of those.