This is an exercise in words, going completely through the dictionary and saying what each entry brings to mind or my interpretation of the word.  I  love words

a   -  the very first letter we are all introduced to in the English language.

aback  -  I was probably first taken aback or disconcerted when an adult slapped my hand for doing      
something that they considered wrong.

abacus  - I first heard of this from senior high school students, never getting to those higher grades, I never
really knew how a abacus worked.