reciprocal
adjectiveUK /rɪˈsɪprəkl/
US /rɪˈsɪprəkl/
When two people or things give or do the same thing to each other.
The two friends had a reciprocal agreement to help each other with homework.
OTHER MEANINGS
2. In mathematics, the number you multiply by to get one, like flipping a fraction upside down.
The reciprocal of 4 is one quarter.
3. Given or felt by each side toward the other in return.
She felt reciprocal affection for her pen pal.
4. A thing that is given or done in return for something else.
He offered a small gift as a reciprocal for their kindness.