serious
adj.adj. important or needing a lot of thought and care. You use it to describe things that are not jokes and people who do not laugh much.
adj. demanding careful consideration due to importance or potential danger; not lighthearted or superficial in character.
We need to have a serious talk about your future.
The doctor said the injury is serious and requires immediate surgery to prevent further damage.
While the initial reports were dismissed as rumors, the government eventually issued a serious warning regarding the economic stability of the region.
From Middle English seryows, from Old French serieux, from Medieval Latin sēriōsus, an extension of Latin sērius (“grave, earnest, serious”), from Proto-Indo-European *swer- (“heavy”). Cognate with German schwer (“heavy, difficult, severe”), Old English swǣr (“heavy, grave, grievous”). More at swear, sweer.
Typically precedes the noun it modifies or follows a linking verb like 'be' or 'become'.