deleterious

/ˌde-lə-ˈtir-ē-əs/

Greek dēlētērios, from dēleisthai to hurt

adjective

  1. harmful often in a subtle or unexpected way

deleterious effects

pernicious baneful noxious deleterious detrimental mean exceedingly harmful. pernicious implies irreparable harm done through evil or insidious corrupting or undermining. baneful implies injury through poisoning or destroying.