Learn Hardcore Dutch: De reden blijft onbekend.

De is the definite article for singular common-gender nouns in Dutch. It corresponds to the in English. Most Dutch nouns take de, while a smaller set of neuter nouns takes het.

Why is it de and not het before reden?

Dutch nouns are divided into two grammatical genders: common (de-words) and neuter (het-words). Reden is a common-gender noun, so it always uses de. There’s no reliable rule to predict gender—you simply learn which nouns are de-words and which are het-words.

What does reden mean, and what part of speech is it?

Reden is a noun meaning reason (or sometimes cause). It’s singular here; its plural would be redenen (reasons).

What is blijft, and why does it end in -t?

Blijft is the third-person singular present tense of the verb blijven (to remain/stay). In Dutch, most verbs add -t for the hij/zij/het (he/she/it) form in the present tense:
• ik blijf (I remain)
• jij blijft (you remain)
• hij/zij/het blijft (he/she/it remains)