Are you able?

I spent my day today cooped up in a room with a bunch of women.  I realize that's sort of the story of my life as I'm an elementary school teacher, but still.  Today's topic was spelling instruction, and writing instruction.  Both worthy topics.  I stayed tuned during the spelling, but by the time writing came around I was pretty much done.  My attention is not easily held after being stuck in one spot for that long.  So, though my afternoon was a waste, I did learn something interesting this morning - the mystery of -ible vs. -able.

It turns out that -ible is used with root words and -able is used with base words.  "What's the difference?"  You ask?  Well let me illuminate you.  A root is part of a word that cannot stand by itself - terr, feas, sens, etc. whereas a base word can stand by itself.  So, if it's a base word, you add -able i.e. movable, likable, suitable, allowable.  Helpful hint 2 - the -able suffix is used with verbs.  If it's just a root, add -ible i.e. permissible, visible, divisible, edible etc.  There are, as with all rules, exceptions - flexible, digestible - but it's a good rule of thumb. :)