adjective
gratuitous
Done or included without a good reason.
Kicking apart her sandcastle is an act of gratuitous destruction.

Etymology
The older meaning was freely given or without payment. The sense shifted from requiring no return to having no sufficient justification, as with an unnecessary insult or detail.
In context
a Chinese restaurant called Wok and Roll, on H Street in Washington. (Laughter) And it's not completely gratuitous, because "wok" and "roll" -- Chinese food and Japanese foods, so it kind of works out.
More examples
- The film’s gratuitous violence added nothing to the story.
- His remark was a gratuitous attack on someone uninvolved.
- She objected to the gratuitous detail in the report.
Forms
gratuitous
Similar words
- unnecessary
- Unnecessary is not needed; gratuitous can also suggest being unjustified or offensively uncalled-for.
- unwarranted
- Unwarranted lacks justification; gratuitous can emphasize an unnecessary addition, attack, or offense.