obnoxious
adj.
1580s, "subject to the authority of another," from Latin obnoxiosus "hurtful, injurious," from obnoxius "subject, exposed to harm," from ob "to, toward" (see ob-) + noxa "injury, hurt, damage entailing liability" (see noxious). Meaning "subject to something harmful" is 1590s; meaning "offensive, hateful" is first recorded 1670s, influenced by noxious.
Obnoxious has two very different senses, one of which (exposed or open or liable to attack or injury) requires notice because its currency is now so restricted that it is puzzling to the uninstructed. It is the word's rightful or de jure meaning, and we may hope that scholarly writers will keep it alive. [Fowler]
Related: Obnoxiously; obnoxiousness.〔李〕[ob-=against 反对；noxi=harm 伤害；-ous a.=having 有…的 ⇒“having harm against 对…有害的”→] a. very disagreeable；offensive；hateful 令人非常不快的；令人讨厌的；反感的