My favorite word is "word." This has been so for a very long time. I use the word "word" very often. "Word" is a great word. It works on so many levels.
To be in agreement with a statement:
"Those shoes are hideous."
To answer “yes” to a question:
"Are familiar with the quadratic equation?"
To express delight:
"My parents died, but they left me a buttload of cash!"
To be used as a question after a statement, in the place of "Really?":
"I just cured cancer!"
The common meaning:
"A word is a unit of language that carries meaning and consists of one or more morphemes which are linked more or less tightly together, and has a phonetic value."
And, finally, the Microsoft word processing program, Word:
"Dude, Word sucks."