How many Vietnamese words do you know?
Sixteen yes-or-no questions. No account, nothing stored, about a minute. The answer comes back as a range, because sixteen answers cannot honestly give you one number.
Answer for the meaning. Say you know a word only if you could say what it means. Guessing does not raise your score. It makes it wrong.
Keys: ← know it · → don't
How the estimate works
After every answer the test fits a curve over Vietnamese word-frequency data. It looks for the rank where your chance of knowing a word is about half. Then it asks the next word around that point.
The estimate is the area under that curve. That figure differs from the rank you reached, and it is larger.
The test is deliberately not a binary search. That was tried first and it underestimated every time. Knowing a word is probabilistic near your own threshold, so one uncertain answer would narrow the range for good.
The Vietnamese line
Vietnamese runs as Sen on Cognate's map: Vietic, 40,000 dictionary entries, 34,278 example sentences, 0 human recordings. The test draws from the words that can be studied, ordered by how often they appear.
| Frequency band | Rank in the list | Example word | Pronunciation |
|---|---|---|---|
| the first hundred | 100 | con | [kɔn˧˧] |
| around one thousand | 991 | mươn | [mɨən˧˧] |
There are no human recordings for this language yet, so the app speaks these words with the system voice.
Dictionary built from Wiktionary via kaikki.org, with Tatoeba sentences and Lingua Libre recordings. Licensed CC BY-SA; the dictionary is a derived work.
What sixteen questions can tell you
The band comes out about 3.6 times wide from edge to edge. The test shows that width. Rounding it to one figure would claim a precision the answers do not carry.
If you guess
The estimate goes wrong, and past a point the test can tell. Say yes to all sixteen, including words at the far end of the dictionary, and you get no number at all.
What is stored
Nothing. The test runs in your browser and there is no account. No answers are sent anywhere. The word list is a static file your browser downloads once.