The day before yesterday
A very common, slightly more informal alternative, especially in Mexico, Central America, and Colombia.
Literally 'it makes two days', this means 'two days ago' and is a common way to express the same time frame.
The day before yesterday I went to the supermarket with my mom.
I received your message the day before yesterday at night.
Did you see the new movie? I saw it two days ago.
The problem with the car started the day before yesterday.
'Anteayer' is the standard, universally understood term. 'Antier' is also widely used and understood, though its frequency varies by country.
'Antier' is extremely common and is often used more frequently than 'anteayer' in everyday, casual conversation.
Both 'anteayer' and 'antier' are commonly used and are interchangeable in most contexts.
'Anteayer' is the standard and preferred term. 'Antier' is considered archaic or a regionalism and is rarely used in modern speech.
'Anteayer' is the most common and standard term. While 'antier' might be understood, it is not commonly used.
Saying 'el día antes de ayer'. — This is a direct translation from English, but it's incorrect. Spanish uses a single compound word: 'anteayer' (ante- meaning 'before' + ayer meaning 'yesterday'). Always use 'anteayer' or 'antier'.
Using the wrong tense with 'anteayer'. — Because 'anteayer' refers to a specific, completed time in the past, you must use the preterite tense (pretérito indefinido). For example, say 'Anteayer comí pizza' (I ate pizza), not 'Anteayer comía pizza' (I was eating pizza).
Confusing 'anteayer' with 'pasado mañana'. — 'Anteayer' means 'the day before yesterday' (in the past). 'Pasado mañana' means 'the day after tomorrow' (in the future). They are opposites, but their similar structure can confuse beginners.