Spanish vocabulary · Beginner

Serious in Spanish: Serio

Serio · adjective · SEH-ryoh

Serio is the Spanish adjective for serious, describing both a person's demeanor and the gravity of a situation. For serious medical conditions, accidents, or threats, grave is the more precise choice. Serio follows standard adjective agreement: serio for masculine, seria for feminine, serios and serias for plurals.

Say SEH-ryoh, with the stress on the first syllable. The io blends into a single glide at the end.

Mi padre es una persona muy seria pero cariñosa.

My father is a very serious but affectionate person.

Serious in Spanish: Quick Reference

Below are the most common Spanish words for serious, with pronunciation and regional usage notes.

SpanishEnglishPronunciationRegion / Register
serioseriousSEH-ryohDefault, widely understood
graveseriousfor serious situations, injuries, or illnesses

How Native Speakers Use Serio

Real example sentences across three contexts you'll actually run into.

Describing a person's personality

El profesor nuevo parece muy serio, pero en realidad tiene buen sentido del humor.

The new professor seems very serious, but he actually has a good sense of humor.

Serio describes someone who appears solemn, focused, or not prone to joking.

A serious conversation

Tenemos que tener una conversación seria sobre nuestro futuro.

We need to have a serious conversation about our future.

Serio modifies topics, conversations, and situations that require gravity.

A grave medical situation

El accidente fue grave y tuvieron que llevarlo al hospital de inmediato.

The accident was serious and they had to take him to the hospital immediately.

Grave is preferred over serio when describing the severity of injuries, illness, or emergencies.

Avoid These Mistakes When Using Serio

Using serio for a medical emergency

Incorrect: El paciente está serio.

Correct: El paciente está grave.

When describing someone's critical medical condition, grave is the correct adjective. Serio would imply the patient has a stern facial expression, not that their condition is life-threatening.

Forgetting gender agreement

Incorrect: Ella es muy serio.

Correct: Ella es muy seria.

Serio must match the gender of the noun it modifies. For feminine subjects, use seria. For plural groups, use serios or serias.

Lock in Serious Vocabulary with the Parrot Method

Why word lists alone don't stick

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See Serio used by native speakers

Parrot's short-form videos feature native speakers using serio in real situations. Context-based exposure beats flashcards, you hear Mi padre es una persona muy seria pero cariñosa. while watching someone live the moment, connecting meaning, sound, and rhythm at once.

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Common Questions About Serious in Spanish

How do you say serious in Spanish?
The direct translation is serio (masculine) or seria (feminine). When describing a person, it means solemn or earnest. For describing a critical situation like an illness or accident, use grave instead.
What is the difference between serio and grave?
Serio describes a personality trait or a conversation that demands careful attention. Grave describes severity — a grave illness, a grave accident, a grave mistake. You would not call a car crash serio; you would call it grave.
Can serio mean reliable in Spanish?
In business and professional contexts, calling someone serio often means they are reliable, responsible, and trustworthy. For example, es un proveedor muy serio means he is a very reliable supplier, not that the supplier is humorless.