English Reference

Word

seriously

Phoneticsse·ri·ous·ly, stress on the first syllable

US/ˈsɪɹiəsɫi/

UK/sˈiəɹɪəsli/

Adverb of manner

Definitions

01not joking

B1 · Intermediate

adv. in a way that is not joking or playful.

adv. in a literal, earnest, or solemn manner; without levity.

“I am seriously considering moving to another country for work.”

“The board is seriously evaluating the proposal, as the potential for long-term growth outweighs the immediate financial risks.”

Usage

usually follows the verb or sits at the end of the clause.

02very much or badly

B1 · Intermediate

adv. to a great or dangerous degree.

adv. to a severe or critical extent; used to intensify negative states or injuries.

“Several people were seriously injured in the car accident last night.”

“The local ecosystem was seriously affected by the chemical spill, requiring years of intensive restoration efforts.”

Usage

often modifies adjectives like 'injured', 'ill', or 'damaged'.

Antonyms

03changing to a serious topic

B2 · Upper Intermediate Informal

adv. you use this to stop joking and start talking about something important.

adv. used as a sentence adverb to signal a transition from a humorous or lighthearted tone to a sincere one.

“Seriously, we need to decide who is driving to the wedding.”

“Seriously though, if we don't address the budget deficit now, we won't have any funding for next year's projects.”

Usage

usually placed at the very beginning of a sentence.

Teaching tip

This is a 'discourse marker' that helps manage the flow of a conversation.

Synonyms

honestlyjoking aside

04showing disbelief

B1 · Intermediate Informal

adv. you say this when you are surprised or cannot believe what someone said.

adv. used as an exclamation or a question to express incredulity, annoyance, or emphasis.

“Seriously? You spent two hundred dollars on a pair of shoes?”

“Seriously? After all the help I gave him, he didn't even bother to send a thank-you note.”

Usage

often stands alone as a one-word question.

Teaching tip

In speech, the meaning changes based on intonation; a rising tone shows surprise, while a falling tone shows annoyance.

Synonyms

05extremely

B2 · Upper Intermediate Informal · Slang

adv. very or extremely; used to make an adjective stronger.

adv. used as a high-intensity degree adverb to modify adjectives.

“That new video game is seriously cool.”

“The view from the top of the mountain was seriously impressive, making the four-hour climb feel entirely worth the effort.”

Usage

placed immediately before the adjective it modifies.

Teaching tip

This is very common in youth slang and casual digital communication.

Collocations

Common phrases and expressions where native English speakers use the word “seriously” in context.

Verb

01. seriously affect

“The heavy rain could seriously affect the traffic this morning.”

adv + verb

02. seriously injured

03. seriously indeed

Etymology

From Middle English seriously, sereously, ceryously, seryowslech (“earnestly”), equivalent to serious + -ly.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

Word family

ADJECTIVE

ADVERB

seriously(B1)

Idioms

This entry

Exam level
CambridgeCambridgeCambridge English QualificationsThe exam suite from Cambridge University Press & Assessment, from A1 Movers up to C2 Proficiency. The benchmark names double as CEFR labels.B1 PreliminaryIELTSIELTSInternational English Language Testing SystemThe 0–9 band test co-owned by the British Council, IDP, and Cambridge. Used for university entry, work, and migration.4.0–5.0TOEFL iBTTOEFL iBTTest of English as a Foreign Language, Internet-Based TestETS's academic English test, the standard route for US university admissions. Scored 0–120, with a 1–6 scale since 2026.1–6 scale: 3.0–3.544–71TOEICTOEICTest of English for International CommunicationETS's workplace English test, big in Japan and Korea. Listening & Reading scores 10–990 and tops out at C1.550–784
Frequency
Very common
Level
B1 · IntermediateOxford
Updated

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English Reference