Sad
Use this to mean 'saddened' or 'sorry about something.' It's a bit more formal than 'triste'.
This means 'discouraged,' 'down,' or 'unenthusiastic.' It's for when you lose motivation or feel a bit blue.
A very common, informal slang term in some countries for 'bummed out' or 'down in the dumps'.
I am sad today.
Why are you sad, Ana?
The end of the movie is very sad.
My dog is sick and I'm a little down.
They are sad because the vacation is ending.
The word 'triste' is universally understood and is the standard term across all Spanish-speaking countries.
It's common to hear 'agüitado/a' (ah-gwee-TAH-doh) in casual conversation, which means something like 'bummed out' or 'down'.
The slang term 'bajoneado/a' is extremely common for feeling 'down' or 'bummed out', from the noun 'bajón' (a downer).
In some contexts, 'aburrido/a' (which usually means 'bored') can be used to mean 'sad' or 'down'. For example, 'Estoy aburrido en la casa' can mean 'I'm sad/down at home'.
While 'triste' is the main word, 'estar de bajón' is a common expression for 'to be down' or 'to feel low'.
Using 'ser' instead of 'estar'. Saying 'Soy triste' means 'I am a sad person' (a personality trait). — Always use 'estar' for feelings. Say 'Estoy triste' to mean 'I am feeling sad right now'.
Forgetting to match the adjective to the person. For example, 'Ellos está triste'. — Adjectives must agree in number. The plural form is 'tristes'. Correct: 'Ellos están tristes'.
Using the noun 'tristeza' (sadness) instead of the adjective 'triste' (sad). Saying 'Estoy tristeza' is incorrect. — You need the adjective to describe how you feel. The correct phrase is 'Estoy triste'.