Senses
不齿/ 不齒 to despise
To despise or hold in contempt; to refuse to associate with someone or view them as an equal.
不齿/ 不齒 to not employ
(literary) To remove from a registry of officials or social rank as a punishment; to strip of status or employment
不齿/ 不齒 to not rank by age
(archaic) To not follow the standard order of seating by age, specifically referring to high-ranking officials who are seated by rank instead.