Gratuitous
Part of speech: adjective
Definition: Given freely; unearned. Not called for by the circumstances; uncalled for; without reason, cause, or proof; adopted or asserted without any good ground; unjustified.
Example sentence: Two things I do well in books are sex and violence, but I don't want gratuitous sex or violence. The sex and violence are only as graphic as need be. And never included unless it furthers the plot or character development.
Complimentary
Part of speech: adjective
Definition: In the nature of a compliment.Free; provided at no charge.With respect to the closing of a letter, formal and professional.