dì​sān​zhě

number three

第三者 dì​sān​zhě
number three pronoun
The third person or item in a list, sequence, or series.

Among the three proposals listed, the third one is the most difficult to achieve.

the other person noun
A person who is romantically involved with someone already in a committed relationship, such as a husband or wife.

Their marriage eventually broke up due to the involvement of a third party.

third party numeral
A person or entity besides the two primarily involved in a situation, dispute, or legal agreement; a disinterested party.

Car owners must purchase third-party liability insurance.

Frequency

Movie subtitles
2.15 per million appears in 1% of films
Written text
5.15 per million

Sources

Definitions
CC-CEDICT