serious (adj.)
- abandoned
- acute
- afire
- alarming
- ardent
- arduous
- austere
- awe-inspiring
- bad
- bound
- burning
- businesslike
- cogitative
- cognitive
- committed
- comprehensive
- conceptive
- conceptual
- consequential
- considerable
- contemplative
- critical
- crucial
- dangerous
- decided
- decisive
- decorous
- dedicated
- deep
- definite
- deliberative
- demure
- determined
- devoted
- devout
- difficult
- dignified
- dour
- earnest
- elevated
- exhaustive
- explosive
- faithful
- fatal
- fateful
- fell
- fervent
- fervid
- fiery
- flaming
- formal
- formidable
- frowning
- full
- genuine
- grand
- grave
- great
- grievous
- grim
- hearty
- heated
- heavy
- honest
- hot
- hot-blooded
- humorless
- impassioned
- important
- imposing
- inspiring
- intense
- intent
- introspective
- irresistible
- laborious
- life-and-death
- life-or-death
- lofty
- long-faced
- loyal
- main
- majestic
- major
- maximum
- meditative
- menacing
- mental
- mighty
- moderate
- momentous
- moving
- musing
- nasty
- no-nonsense
- noble
- noetic
- obstinate
- operose
- parlous
- passionate
- pensive
- perfervid
- perilous
- persevering
- persistent
- plenary
- poker-faced
- pondering
- portentous
- powerful
- precarious
- prehensive
- pressing
- purposeful
- red-hot
- reflecting
- reflective
- relentless
- resolute
- resolved
- ruminant
- ruminative
- sedate
- serious-minded
- severe
- significant
- sincere
- single-minded
- sober
- sobersided
- solemn
- somber
- speculative
- spirited
- staid
- stately
- steady
- stern
- straightforward
- strenuous
- strong
- sublime
- temperate
- tenacious
- thinking
- thought
- thoughtful
- threatening
- total
- tough
- ugly
- unfunny
- unsmiling
- urgent
- vehement
- vital
- warm
- weighty
- white-hot
- wholehearted
- wistful
- zealous
He said they that were serious in ridiculous matters would be ridiculous in serious affairs.
And wine can of their wits the wise beguile,
Make the sage frolic, and the serious smile.
Yet sometimes, when the secret cup
Of still and serious thought went round,
It seemed as if he drank it up,
He felt with spirit so profound.
