How many letters does a word have to contain to be considered a word in the english language?

Question

How many letters does a word have to contain to be considered a word in the english language?

Answer 1

one

A

Answer 2

One.  A is a word.  I is a word.

Answer 3

One. "A" is a word.

Answer 4

one or more, a is a word as well as a letter.

Answer 5

One

Answer 6

one   Aor I or O can be considered a word  

Answer 7

One.