harm
verb
hɑːm 
hɑːrm Idioms
see not harm/hurt a fly at fly noun, not harm/touch a hair of somebody's head at hair
Usage note: damagehurt harm impairThese words all mean to have a bad effect on somebody/something.damage to cause physical harm to something, making it less attractive, useful or valuable; to have a bad effect on somebody/something's life, health, happiness or chances of success: The fire badly damaged the town hall. ◇ emotionally damaged childrenhurt (rather informal) to have a bad effect on somebody/something's life, health, happiness or chances of success: Hard work never hurt anyone.harm to have a bad effect on somebody/something's life, health, happiness or chances of success: Pollution can harm marine life.damage, hurt or harm?Hurt is slightly less formal than damage or harm, especially when it is used in negative statements: It won't hurt him to have to wait a bit. ◇ It won't damage/harm him to have to wait a bit. Harm is also often used to talk about ways in which things in the natural world such as wildlife and the environment are affected by human activity.impair (rather formal) to damage somebody's health, abilities or chances: Even one drink can impair driving performance.to damage/hurt/harm/impair somebody's chancesto damage/hurt/harm somebody's interests/reputationto damage/harm/impair somebody's healthto seriously/greatly damage/hurt/harm/impair somebody/somethingto badly/severely damage/hurt/impair somebody/something