Serious

a.	1.	Grave in manner or disposition; earnest; thoughtful; solemn; not light, gay, or volatile. He is always serious, yet there is about his manner a graceful ease. - Macaulay.
	2.	Really intending what is said; being in earnest; not jesting or deceiving.
	3.	Important; weighty; not trifling; grave. The holy Scriptures bring to our ears the most serious things in the world. - Young.
	4.	Hence, giving rise to apprehension; attended with danger; as, a serious injury.

Adj.	1.	serious - concerned with work or important matters rather than play or trivialities; "a serious student of history"; "a serious attempt to learn to ski"; "gave me a serious look"; "a serious young man"; "are you serious or joking?"; "Don't be so serious!" Antonyms: frivolous - not serious in content or attitude or behavior; "a frivolous novel"; "a frivolous remark"; "a frivolous young woman"
	2.	serious - of great consequence; "marriage is a serious matter"
	3.	serious - causing fear or anxiety by threatening great harm; "a dangerous operation"; "a grave situation"; "a grave illness"; "grievous bodily harm"; "a serious wound"; "a serious turn of events"; "a severe case of pneumonia"; "a life-threatening disease" Synonyms: grievous, life-threatening, dangerous, grave, severe
	4.	serious - appealing to the mind; "good music"; "a serious book" Synonyms: good
	5.	serious - completely lacking in playfulness Synonyms: unplayful, sober
	6.	serious - requiring effort or concentration; complex and not easy to answer or solve; "raised serious objections to the proposal"; "the plan has a serious flaw"

abandoned, acute, afire, ardent, arduous, austere, awe-inspiring, bad, bound, bound and determined, burning, businesslike, cogitative, cognitive, committed, comprehensive, concentrating, concentrative, conceptive, conceptual, conceptualized, consequential, considerable, contemplating, contemplative, crucial, dangersome, decided, decisive, decorous, dedicated, deep, definite, deliberating, deliberative, demure, determined, devoted, devout, difficult, dignified, dour, elevated, excogitating, exhaustive, explosive, faithful, fatal, fateful, fell, fervent, fervid, fiery, flaming, formal, formidable, fraught with danger, frowning, full, genuine, grand, grievous, grim, grim-faced, grim-visaged, hearty, heated, heavy, honest, hot, hot-blooded, humorless, ideative, impassioned, imposing, in earnest, inspiring, intense, intent, intent on, introspective, irresistible, jeopardous, laborious, life-and-death, life-or-death, lofty, long-faced, loyal, main, majestic, major, maximum, meditating, meditative, menacing, mental, mighty, moderate, moving, museful, musing, nasty, no joke, no laughing matter, no-nonsense, noble, noetic, obstinate, on fire, operose, parlous, passionate, pensive, perfervid, periculous, perilous, persevering, persistent, plenary, poker-faced, pondering, portentous, powerful, precarious, prehensive, pressing, purposeful, red-hot, reflecting, reflective, relentless, resolute, resolved, ruminant, ruminating, ruminative, serious-minded, severe, significant, sincere, single-minded, sober-minded, sobersided, somber, speculative, spirited, stately, steady, stern, stone-faced, straight-faced, straightforward, strenuous, strong, sublime, temperate, tenacious, thinking, thought, thoughtful, threatening, total, tough, ugly, unamusing, unfunny, unsmiling, urgent, vehement, vital, warm, weighty, white-hot, wholehearted, wistful, zealous