Learn Dutch: Ik zie dat parapluutje in de kast. - I see that little umbrella in the cabinet.

The base noun is paraplu. In Dutch, a single open vowel at the end of a word is pronounced long. When we add the diminutive ending -tje, that vowel is no longer at the end of the word. To keep the long 'u' sound before the consonants, we must double it to uu. So, paraplu becomes parapluutje.

How do I know to use the suffix -tje instead of just -je for this diminutive?

Nouns that end in a vowel (like the 'u' in paraplu) generally take the suffix -tje. When you combine this with the spelling rule from this lesson, you double the long vowel and add -tje, which is why we get parapluutje. Another example is auto, which becomes autootje.

Why do we use dat for the umbrella instead of die? I thought it was 'de paraplu'.

You are right that the base word is de paraplu. However, in Dutch, all diminutive words become het words, no matter their original gender. Because it is het parapluutje, we must use the neuter demonstrative pronoun dat (that) instead of die.

Can I translate kast as 'closet' or 'wardrobe' instead of 'cabinet'?