Noun plurals

Multi-syllable nouns ending in an unstressed -s are identical in singular and plural, and the article carries the entire distinction. It also carries meaning: el lunes is 'on Monday', los lunes is 'on Mondays'. Stress that final syllable, or take a one-syllable noun, and the rule flips back to normal: el inglés, los ingleses; el mes, los meses.

Look at the last letter. After a vowel, add -s: casa, casas. After a consonant, add -es: señor, señores. A final -z is written c before that e, so vez becomes veces. Those three moves pluralise almost every noun you know.

The article and every adjective go plural with the noun: la casa blanca, las casas blancas. Gender still decides los or las, so los días despite the -a. Adding -es adds a syllable, so a written accent can drop: la canción, las canciones.