Winter – el invierno
(Pronounced in-byair-no)
To remember that winter is pronounced in-byair-no (invierno) in Spanish, use the following mnemonic:
It must be winter, there's a nip in the air, no? (invierno).

Invierno is masculine, so it’s el invierno. Imagine making snow elephants in winter instead of snowmen:

Examples of invierno (winter) in a sentence
En invierno, me gusta tomar chocolate caliente.
(In winter, I like to drink hot chocolate.)
El invierno en Madrid puede ser muy frío.
(The winter in Madrid can be very cold.)
Durante el invierno, los árboles pierden sus hojas.
(During the winter, the trees lose their leaves.)