From the oblique stem of Latin coitiō.
coition (usually uncountable, plural coitions)
- Sexual intercourse.
1650, Thomas Browne, Pseudodoxia Epidemica: […], 2nd edition, London: […] A. Miller, for Edw[ard] Dod and Nath[aniel] Ekins, […], OCLC 152706203:
their coition is made by supersaliency, like that of horses, as we are informed by some who have beheld them in that act