1. Suffix: ious, eous
What does the suffix ‘ous’ ‘ious’ ‘eous’mean? ‘having qualities of’
Both of these endings are used to form adjectives (e.g. cautious or hideous). Words ending with -ious are far more common than those ending in -eous, but unfortunately there are no set rules which can help you choose the correct one.
Here are some common adjectives ending in -ious:
ambitious; previous; curious; anxious; delicious; rebellious; religious; serious; envious; superstitious; notorious; glorious; conscious; various; hilarious; ferocious; obvious;  studious; tedious; victorious.
Here are some of the most important ones that end in -eous:
gorgeous; curvaceous; nauseous; erroneous; courteous; plenteous; simultaneous; miscellaneous; spontaneous; gaseous.

2. Suffix: ious, eous
There is also a small group of adjectives that take the spelling -eous when the ending -ous is added.
This is because the root word they are formed from ends in -ge. The most frequently used words like this are:
advantageous, from advantage
courageous, from courage
outrageous, from outrage

3. ABSTRACT NOUNS Nouns can be abstract or concrete.
Concrete nouns are tangible and you can experience them with your five senses. 
Abstract nouns refer to intangible things, like feelings, ideals, concepts and qualities.
Common Abstract Nouns - Showing Human Qualities or Characteristics
Common Abstract Nouns - Showing Human Qualities or Characteristics
Beauty, Bravery, Brilliance, Brutality
Calm, Charity, Coldness, Compassion, Confidence, Contentment, Courage
Curiosity, Dedication, Determination
Ego, Elegance, Enthusiasm, Envy
Evil, Fear, Generosity, Goodness
Graciousness, Hatred, Honesty
Honor, Hope Humility, Humor 
Insanity, Integrity, Intelligence 
Jealousy, Kindness, Loyalty
Maturity, Patience, Perseverance
Sanity, Self-control, Sensitivity
Sophistication, Stupidity
Sympathy, Talent, Tolerance
Trust, Warmth, Weakness
Wisdom, Wit

4. ABSTRACT NOUNS Nouns can be abstract or concrete.
Concrete nouns are tangible and you can experience them with your five senses. 
Abstract nouns refer to intangible things, like feelings, ideals, concepts and qualities.
Common Abstract Nouns - Showing Human Qualities or Characteristics
Showing Emotions/Feelings
Adoration, Amazement, Anger, Anxiety, Apprehension, Delight, Despair, Disappointment, Disbelief,
Excitement, Fascination, Friendship, Grief, Happiness, Hate, Helpfulness, Helplessness, Joy, Love, Misery, Pain, Pleasure, Power, Pride, Relaxation, Relief, Romance, Sadness, Satisfaction, Silliness, Sorrow, Strength, Surprise, Tiredness, Uncertainty,
Wariness, Weariness, Worry