serious

Important enough to need careful attention, often because it could cause harm.

• This is a serious problem.
• Nobody suffered serious injuries in the crash.
• Ignoring that warning could have serious consequences.

Similar words: major, grave, important

Opposites: minor, trivial

Common phrases: serious problem, serious injury, serious damage, serious consequences

Meaning what you say or truly intending to do something, rather than joking.

• Are you serious?
• He was serious when he offered to help.
• I'm serious about learning to swim this year.

How to use it: serious about something/doing something (She is serious about moving abroad.)

Similar words: sincere, in earnest

Opposites: joking, insincere

Common phrases: are you serious, serious about something, completely serious, serious offer

Showing little happiness or humour in your face or behaviour.

• She looked very serious.
• His serious expression made everyone fall silent.
• He was a quiet, serious child who rarely smiled.

Similar words: solemn, grave, unsmiling

Opposites: cheerful, lighthearted

Common phrases: serious expression, serious face, look serious, serious manner