This weeks spellings all use the ous suffix. Adding the ous suffix creates a word that means full of. So a dangerous situation is a a situation full of danger. A joyous occasion like the birth of a baby is a time full of joy.
Each time there is a root word that is added to the suffix ous.
Sometimes the root word stays the same joy + ous = joyous
Sometimes the root word is changed fame + ous = famous (the e is taken off)