An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

Possessed, experienced, performed, etc., by each of two or more with respect to the other; reciprocal.

M.E., from M.Fr. mutuel, from L. mutu(us) "reciprocal, done in exchange," from PIE base *mei- "to change," → mutation.

Dosuyé from do, → two, + su "side, direction," from Mid.Pers. sôk "direction, side" + nuance suffix -é.

In → probability theory, of or pertaining to two → events A and B, if they cannot occur together, i.e. the occurrence of one precludes the occurrence of the other: A ∩ B = 0.

→ mutual; → -ly; → exclusive.