Word is unbroken sequence of characters.
Each word is associated with surface concept by word dictionary.
Example:
“Boy”,
“like”, “345”, “Max87”, “Boeing-747” are words.
“Boy likes Boeing-747”, “3 4 5”, “Max 87” are not words. (They are phrases).
Punctuation
marks (“.”, “,”, “;”, “!”) are words.
Therefore “Mama!”
is not a word. It is a phrase,
which consists of two words: “Mama” and “!”.