Apart from a very small amount of words, ‘-ness’ almost always marks a noun.
BUSINESS
FITNESS
AWARENESS
ILLNESS
HAPPINESS
EFFECTIVENESS
DARKNESS
CONSCIOUSNESS
WEAKNESS
THICKNESS
WITNESS
GOODNESS
WILDERNESS
WELLNESS
BRIGHTNESS
WILLINGNESS
KINDNESS
MADNESS
FORGIVENESS
SICKNESS
READINESS
FAIRNESS
RIGHTEOUSNESS
SADNESS
HARNESS
SWEETNESS
WITNESS (VVI)
GREATNESS
WELLNESS (NP1)
STIFFNESS
REDNESS
HOMELESSNESS
HOLINESS
OPENNESS
USEFULNESS
DIZZINESS
BLINDNESS
HARDNESS
MINDFULNESS
COMPETITIVENESS
GUINNESS (NP1)
LONELINESS
RICHNESS
SERIOUSNESS
BITTERNESS
FRESHNESS
SHARPNESS
LIKENESS
FULLNESS
CLEANLINESS
WITNESS (NN1_VV0)
UNIQUENESS
TENDERNESS
COMPLETENESS
RESPONSIVENESS
PREPAREDNESS
WITNESS (VV0)
HARNESS (VVI)
DRYNESS
CORRECTNESS
SOFTNESS
TOUGHNESS
HARNESS (NN1_VV0)
NUMBNESS
SHORTNESS
SORENESS
TIGHTNESS
LIGHTNESS
WICKEDNESS
SMOOTHNESS
WITNESS (VV0_NN1)
ATTRACTIVENESS
EYEWITNESS
SELF-AWARENESS
EMPTINESS
SELFISHNESS
FIRMNESS
FRIENDLINESS
LAZINESS
APPROPRIATENESS
CLOSENESS
FAITHFULNESS
TIREDNESS
FONDNESS
NERVOUSNESS
AWESOMENESS
INVERNESS (NP1)
RANDOMNESS
STILLNESS
ALERTNESS
TIMELINESS
ONENESS
INDEBTEDNESS
UNWILLINGNESS
UNHAPPINESS
CRAZINESS
DROWSINESS
QUICKNESS
RESTLESSNESS
HOPELESSNESS