Boo-boo
A boo-boo was children's slang for a minor injury.
In 2375, The Doctor characterized a brig-imprisoned Tom Paris's head injury as being "what Naomi Wildman refers to as a boo-boo". Starved for socialization, Paris begged (unsuccessfully) The Doctor to take him to sickbay for tests, or grant him a medical reprieve - anything to end his solitary confinement. (VOY: "Thirty Days")