plurals  A plural is more than one.  we,us,they,them,people.  A singular is one as it explains in the name "single”

Same letters  Same letters are words with the same letter in but different sound.  Here are some examples: Foot Food Mould Could

Ible and able  The rule with ible and able is that words ending with ible are not root words on there own without the ible.  Able words are root words on there own without the able. E.G Impossible Imposs Capable cap

Tial and Cial  Tial words are either false words or words with E at the end.  Cial words are root words on there own.

Root words  Root words are two words that join up to make another word.  E.G Power, full Sometimes you have to take letters away powerful.