affirmative

Short definition from Wiktionary

Adjective

1. 1
   pertaining to truth; asserting that something is; affirming
2. 2
   pertaining to any assertion or active confirmation that favors a particular result
3. 3
   positive
4. 4
   Confirmative; ratifying.
5. 5
   Dogmatic.
6. 6
   Expressing the agreement of the two terms of a proposition.
7. 7
   positive; not negative

Noun

1. 1
   Yes; an answer that shows agreement or acceptance.
2. 2
   An answer that shows agreement or acceptance.
3. 3
   An assertion.

Interjection

1. 1
   Yes.
2. 2
   Yes; true; correct.